I have a Bluebird 440, which I bought secondhand.
As far as the regulator goes, is it just supposed to sit on top of it's space on the barrel, or is the plastic plate supposed to be secured somehow?
There should be a black rubber gasket around the bottom of the clear plastic plate. According to the manual, it should be enough to create a tight seal when the vacuum is turned on. If yours did not come with a a gasket, you might be able to buy one from Bluebird.
For me the gasket does not work, because the pugmill has some (I believe) limescale buildup on the lip of the barrel, the surface is not smooth enough to make a seal with the gasket. The person I bought it from said she would put a coil of clay around the lip of the barrel, in order to create a tight seal. If your gasket is missing or does not work, this would be a quick solution for you, if you only plan to use it a few times before selling it. In my case I wanted a more permanent solution, so I made a homemade gasket with silicone caulk. I wrapped the top of the barrel, and the plastic plate, with Glad Press-n-Seal wrap, squeezed a bead of caulk on the lip of the barrel, set the plastic plate on top, then waited a few days for the caulk to cure. Then I peeled off the Press-n-Seal wrap, and now I have a dry caulk gasket that makes a nice tight seal and lasts for a few years.
Closed. And as far as I know, nothing goes on top of the valve. I don't think you are missing anything.
And the valve that the pump is attached to, should this be closed (can't see the hole) or open? I know sounds pretty basic but I'm not real sure exactly how this confounded contraption functions. And does something go on the top side of this valve? The hose to the compressor is on the bottom side, but wanted to make sure I'm not missing something.
The spring-loaded lever will constantly open and close while the pugmill is on. I believe its function is to keep the opening that leads to the vacuum chamber from getting clogged with clay. I don't know if the auger is supposed to hit it, I've never opened up my pugmill that far.
Lastly, the little lever attached to the spring in the chamber under where the regulator sits: what is the function of this? What position should it be in during use? When I turned on the pugmill I could see that the auger was hitting it as it rotated and flicking. Is it supposed to do this, or is some messed up/misaligned?
Lastly, when I got the pugmill I called Bluebird (970-484-3243) and they mailed me the manual. They would probably answer questions on phone too.