Mark C.

When it comes to kilns (and I assume this is an electric only thread) I do it all myself. I have a manual electric skutt (no computer) I added a fire rite control that turns it up as fast or slow as I need. I do not fire this much anymore as most pots are bisqued in my gas kilns. I have rebuilt a few of these type of kilns. pretty easy stuff. Same with shelves I do all the maintenance . I never fire over bisque temps in my 10 cubic skutt.I have upgraded to better connectors (not crimps) and leave all switches on high (the fire rite turns the kiln on and off) I did replace some of the jacket a few years ago and have more jackets in a box but have yet to finish the job..I think I fired this once last year.Its cone sitter kiln for turn off with a safety timer.I did repaint all the contol boxes a  non skutt color when the red color flaked off with rust. I have upgraded to real stainless screws as well so they do not rust. Any time I work on it I make it better with better materials when I can. Thees manuel kilns are pretty bullet proof and go for a long time without trouble.I have had 3 skits over time (all used) and if I bought new one it would be an L&L.
I would hope L&L used better stainless screws and parts. My beef with electric kiln companies is they skimp on quaility on small parts to save a few bucks. The stands are to small and the controls get to hot from lack of space and insulation. The stainless can be of poor quaility as well and rust.Not sure if any manufacture has it all figurted out. I do like the hard element holders  of top brands as well this feature alone is worth it in my view as the bricks break out every element change if there is not hard holder.

You need a damper-I suggets thin broken kiln shelve say 1/2 inch thick so that the weight is minimal -or just a soft brick which is light still
Also I would run as the larger pipe (I thought you said it was 3/4) all the way to kiln. It looks like you necked it down somewhere in last 10 feet with smaller flex? Its usually not a pressure issue with natural gas its a volume issue, so keep the pipe as big as you can to the kiln.
I have those same type of burners on an updraft .  You cannot change your altitude  so you need to have all the other functions perfect 
 

Wondering if a  pipe chimney would draw more  air through, and damper needed for sure.
 

You need a damper-I suggets thin broken kiln shelve say 1/2 inch thick so that the weight is minimal -or just a soft brick which is light still
Also I would run as the larger pipe (I thought you said it was 3/4) all the way to kiln. It looks like you necked it down somewhere in last 10 feet with smaller flex? Its usually not a pressure issue with natural gas its a volume issue, so keep the pipe as big as you can to the kiln.
I have those same type of burners on an updraft .  You cannot change your altitude  so you need to have all the other functions perfect 
 

You need a damper-I suggets thin broken kiln shelve say 1/2 inch thick so that the weight is minimal -or just a soft brick which is light still
Also I would run as the larger pipe (I thought you said it was 3/4) all the way to kiln. It looks like you necked it down somewhere in last 10 feet with smaller flex? Its usually not a pressure issue with natural gas its a volume issue, so keep the pipe as big as you can to the kiln.
I have those same type of burners on an updraft .  You cannot change your altitude  so you need to have all the other functions perfect 
 

When it comes to kilns (and I assume this is an electric only thread) I do it all myself. I have a manual electric skutt (no computer) I added a fire rite control that turns it up as fast or slow as I need. I do not fire this much anymore as most pots are bisqued in my gas kilns. I have rebuilt a few of these type of kilns. pretty easy stuff. Same with shelves I do all the maintenance . I never fire over bisque temps in my 10 cubic skutt.I have upgraded to better connectors (not crimps) and leave all switches on high (the fire rite turns the kiln on and off) I did replace some of the jacket a few years ago and have more jackets in a box but have yet to finish the job..I think I fired this once last year.Its cone sitter kiln for turn off with a safety timer.I did repaint all the contol boxes a  non skutt color when the red color flaked off with rust. I have upgraded to real stainless screws as well so they do not rust. Any time I work on it I make it better with better materials when I can. Thees manuel kilns are pretty bullet proof and go for a long time without trouble.I have had 3 skits over time (all used) and if I bought new one it would be an L&L.
I would hope L&L used better stainless screws and parts. My beef with electric kiln companies is they skimp on quaility on small parts to save a few bucks. The stands are to small and the controls get to hot from lack of space and insulation. The stainless can be of poor quaility as well and rust.Not sure if any manufacture has it all figurted out. I do like the hard element holders  of top brands as well this feature alone is worth it in my view as the bricks break out every element change if there is not hard holder.

I use a shop blender for all zinc =think zinc margarita and blend away then add that measure beaten zinc to bucket and sieve normally.

I tend to want to finish work than dry slowly. I use plastic sheets from laundry bags (for delicate work) to thicker plastic from my banana boxes which has some holes in it.
So say handles throw dry on plaster and handle same day cover that night and then dry fast 
If its slab built fish than its cover  with plastic sheets and keep in cooler place either down a few levels  in shop or is shade outside in summer-depending on the season .
I have not had a wet box since collage-(thats 48 years ago) I'm way more into drying faster than slowing the work down.Its a production potter thing .Now some work like teapost need to slow and again it wrap in plastic and keep on lower level in shop. I may be done making teapots come to think about it.

Good question I post my yearly firings for many years here and did so a few weeks ago
here 
 

testing is the only way to know and they both need to be the same temp maturing clays for best results

My 1st wheel I ever bought wasa model C blue motor from Robert Brent Himself in 1970 .  That motor is a 1/2 hp. The orginal models had a steel shallow standard electrical  box  that was way to small-If I recall is was what is called a duplex or square box. Anyway the blue motors cannot be serviced by you but can be by a motor shop. Motor shops are placed that work on Industrial electric motors near mill towns or lumber towns or anyplace that has lots of industrial motors. They can replace the bearings and brushes on that motor as well as give you info on that motor from inside plate info thats not available to you. You do not want to take this motor apart as I have and its a motor shop job to get it back together-trust me on this knowledge.I have sent a few to local motor shop and they fixed them all for reasoable fees. If you ever want a new one Brent sells a comparable  1/2 hp motor and its very spendy $$.. 
That wheel came with a galvanized steel splash pan and mine risted apart by the mid 80s. Now the  wheels come with what I call new plasic Brent splash pans, and they are held in place with flanged bearing on top of the deck which yours does not have. That splace pand will still work but will float around as the flange is not there. When you buy a new wheel head it has this flange. Also of note that motor shaft  you have and your smaller pulley is a diameter that Brent no longer uses (yours is 5/8 if I recall) so if you ever upgrade to a new motor you will need the new 3/4 top smaller pulley as well. That orginal wheel uses two single belts as well-they will last your lifetime. but if you get a new wheelhead you will have to go to the newer 4-6 slot single belt as well
As far as a fuze the 20 amp is for the 120V going in using a slow blow fuze. 20 amp is for #12 wire which was in most home back then for outlets. Today many wheels use less amps but that 20amp is what that motor called out for and is fine to keep using it. Now in terms of the fuze holder and steel box I replaced mine with a new brent plastic box and cover decades ago . No sure if they sell that today but you can use a plasic electrical box and a steel  or plastic cover that you modify. The fuse holder can be bought at a electronic supply online or locally or Amazon.
You need to be handy to assemble all the components into the new box  and mounting it to the deck rail . I would place the fuze holder on the back to keep it dry as thats where all the new ones are underneath not on the front plate but the back of the box
If you have your motor serviced get new brushes and bearings as they are not a greasable type.
Hope some of this clears up the mystery for you
let us know how this turns out please as feed back is always good

Absolutely a different liner looks better in most instances. Its been so long since I even considered that as my stuff always has a different liner glaze

You could empty the mixer and let the bottom dry out and get it out that way and rehydrate it again in small pieces.
welcome to tne forum

testing is the only way to know and they both need to be the same temp maturing clays for best results

Marc commented on using liner glaze,  I have had this happen to me in the past.   I like the looks of liner glaze it gives the piece a higher quality look and the liner gives it a visual break that separates your inner space from the outward spacial design.    Denice

I use a shop blender for all zinc =think zinc margarita and blend away then add that measure beaten zinc to bucket and sieve normally.

I use a shop blender for all zinc =think zinc margarita and blend away then add that measure beaten zinc to bucket and sieve normally.

I tend to want to finish work than dry slowly. I use plastic sheets from laundry bags (for delicate work) to thicker plastic from my banana boxes which has some holes in it.
So say handles throw dry on plaster and handle same day cover that night and then dry fast 
If its slab built fish than its cover  with plastic sheets and keep in cooler place either down a few levels  in shop or is shade outside in summer-depending on the season .
I have not had a wet box since collage-(thats 48 years ago) I'm way more into drying faster than slowing the work down.Its a production potter thing .Now some work like teapost need to slow and again it wrap in plastic and keep on lower level in shop. I may be done making teapots come to think about it.

The easy fix is use a liner glaze on inside and ash glaze on outside-issue is done.
If that sound to hard (an inner and outer glaze job) try- below
Since you are using a iron clay a hotter bisque any help by making sure all organics are burnt out 
yes it looks like the glaze is peeled back clean to me as well. burnouts or ash peeling it back is my guess. Even in oxidation as Kelly said the inners are a slight more reduction  or lets say not as oxidized. One nice liner glaze inside will fix this in a heartbeat

The easy fix is use a liner glaze on inside and ash glaze on outside-issue is done.
If that sound to hard (an inner and outer glaze job) try- below
Since you are using a iron clay a hotter bisque any help by making sure all organics are burnt out 
yes it looks like the glaze is peeled back clean to me as well. burnouts or ash peeling it back is my guess. Even in oxidation as Kelly said the inners are a slight more reduction  or lets say not as oxidized. One nice liner glaze inside will fix this in a heartbeat

The easy fix is use a liner glaze on inside and ash glaze on outside-issue is done.
If that sound to hard (an inner and outer glaze job) try- below
Since you are using a iron clay a hotter bisque any help by making sure all organics are burnt out 
yes it looks like the glaze is peeled back clean to me as well. burnouts or ash peeling it back is my guess. Even in oxidation as Kelly said the inners are a slight more reduction  or lets say not as oxidized. One nice liner glaze inside will fix this in a heartbeat

The easy fix is use a liner glaze on inside and ash glaze on outside-issue is done.
If that sound to hard (an inner and outer glaze job) try- below
Since you are using a iron clay a hotter bisque any help by making sure all organics are burnt out 
yes it looks like the glaze is peeled back clean to me as well. burnouts or ash peeling it back is my guess. Even in oxidation as Kelly said the inners are a slight more reduction  or lets say not as oxidized. One nice liner glaze inside will fix this in a heartbeat

wow Neil said it best ( it'll likely be glowing orange outside the kiln) I will add in no time fast. You need a damper in the chimney they work best about waist height. As he said natural draft burners need the stack (chimney) to be tall and even with your 4 feet more of steel its still way short. I have a stainless steel stack after 8 feet of brick on two kilns. look for that stuff at a salvage yards near beer or pulp mills or any large plant that uses stainless piping. 3/8 is good but still not good enough-Yes you can get some life from it but you still need a damper and way more height.  You can get a fast fire in maybe 8 hours -remember the furniture need to take the heat and cooling as well. I'm not talking lawn chairs I mean the kiln shelves and posts
now to answer the other questions-I would put a digital thermcouple in the door so its swings out of the way and is not in the burner direct path.
If you want to be fancy (i use oxy probes) a oxygen sensor will last longer in the chimney except in your case it may not as the flue flow is so tightly contained. The new to be geil I palces my probe in the flue as it will last many hundreds of  fires before burning out. My other two gas kilns have the sensors in the middle of the load in the doors. They get all of cone 11 so they do burn out in a few  hundred fires. I fire a lot every year over the past 50 years and have a few platinum elements replaced
If you are a beginner really just a good eye is all you need for reductiuon firing-a potter who knows thier stuff would be an asset on the 1st firing or two.
Most newbies put to much gas in thinking more is better-this is where the cheap digital pyrometer come in as it show the exact temps going up or stalling. You need one that goes at a bit more than the cone you are firing to.. 
You need to keep that kiln dry-no rain or snow on it-ever as soft brick and fiber are like sponges and once you dry them out (slow start the 1st fire to dry it out) you want it to stay dry.
What is the flue dimension 8x8?

You could empty the mixer and let the bottom dry out and get it out that way and rehydrate it again in small pieces.
welcome to tne forum

In the 70s silica and talc where what they where-no body knew that silica was 200 mesh or 325-the bags did no say much on them. When I asked most supoppliers only stocked 200 mesh (cheaper) All my silica was 200 mesh.. In the 80s I traded it all to a glass blower for his 325 mesh silica. Later in years the 325 became a thing in many other materials . When you bought talc in 1975 you asked for talc and you got a bag.  (Neph syn was always in 200 or 325 mesh and was the odd one in this choice)There where zero choices. Life was simpler then no shortages, basic commodities, Like coffee now you can have it with  1/2 low fat 1/2 or 2% or all fat or almond milk or austrialian nut juice-well you get the point wayyyy to many choices
In those days the talc was desert talc from Death valley (long ago closed up) or c talc. That has all changes now as well.  Texas talc was a major shift for decades-talc which is grey in color. I now use 3-4 talcs . I only use the 325  in most materils if there is a choice for better melts and yes in the 70s cone  6 was not a thing but 06 was a thing. Back then we had what we called old lady slip shops that sold cone 06 stuff and did mold work (this area had 3 of them) and I got a wholesale accout at one  for some materials and tools(all long gone for 35-40 years now) I knew of NO cone 6 users in the 70s and 80s-none only in the 90s did I become aware of that temp  range. Now I should add I'm in a very high electric rate area maybe the highest in the counrty (Maine I think is higher).
Its made ordering  materials overcomplicated  as well on my side as well.