Im not sure what you mean by a disc sitting on the brass piece. There may have been more then one style used or replaced over the years so maybe???
To answer the second question, I believe there is something to seal the two half of the housing together. Its been awhile since I had mine apart, but there may have been a gasket used.
I do remember digging out a good 3/16" of oil, dirt, grime and whatever out of the valve. Because of the way it was caked on it really looked as if it was a rubber ring of some sort inside, that may be what your seeing. Gas and oil fumes can make their way into the valve via the intake manifold once the engine is shutoff, so over time the valve can get gummed up and stuck.
Im gonna search through my pictures and see if I have any of the assembly.
Jeff
