I have done lots of Brent diagnose work over the years since I bought my 1st Brent from Brent himself back in 69 in LA.
If the wheel does not shut off or does not have enough RPMs take the bottom of foot pedal cover off-you will see a blue and red plastic circle- straight slot small screwdriver will adjust these. They control the low end and high end RPM. I think they are called a potentiometer.
There is a realationship with the off point(wheel stops) and the high rpm point so one will affect the other. If wheel will not stop turning this is the usual cure. I a blue moon its the curcuit board in the controller (located in on off switch box)If the foot pedal will not stop the wheel from turning its most likely the curciut board. Each of these parts seem to be about $75 - 100$ and as Neil says if you want they will diagnose for free if you send them the parts. Its rare the wheel bearing go out as well as motor bruches. If you suspect motor bearings them send the motor and they will inspect and send you back a new motor fo a fee.The guy who knows the most now at Amaco/Brent is Bob-very nice guy.
I throw on a CXC and a C trim on A and have another B for stoneware work as well as an extra B right now. My original model C has a formica flay deck with no plastic ridges.Its orginal foot pedal they stopped making years ago so I upgraded to the newer types as well as swap the head to a 14 inch and have put a new motor on it as I worn the old one out in 20 years-at that time I had to trade out all pullies and belts-also a new controller. Now the old deck made from 1/4 inch plate steel is the only original part left.
I'm a real Brent fan but I also use mine a lot every week.
Brent has been great over the years often sending me free parts especially back in the day-I sent them a whole motor controller set up completely covered in clay a few years ago-Bob Called me and said he likes to see there stuff used and mine was diffently that-he sent back new foot pedal for free and charged me for new curcuit board.
I usually keep a few parts on hand to make my own repairs now.
My next wheel of choice is the Thomas Stuarts-I have liked what I have seen-now that Skutt bought them out I do not know how the quaility is now-Neil has some of the orginals and like them-not sure if he has the newer Skutt ones?
I do not like the high built in splash pan but if you learn on them or are in a teaching situation then this will not be a an issue . I think it more what you are used to. I trim on a Brent with no splash pan as I want the trimmings to fly away.