Ugh camera problems galore, but finally all fixed now. First my om4t got jammed, shutter locked, rewind stuck in down position, manual wind of film rollers did not engage it. Quick fix, popped the bottom plate, removed the double geared assembly held on by three screws, which released the lock and tension. Wind and fire to check, and then replaced carefully and checked.
Problem two, noticed the aperture coupling lever under the lens mount still was sticking after I had swapped the mount, speed ring, and toothed ring assembly. This caused incorrect metering display. Took it all apart and checked all contact surfaces for friction spots or rough patches or warping. Everything was fine, was about to give up but noticed a tiny area of metal was bent from the bottom corner of the metal cover that is on the bottom of the mirror box, which protects the circuit board and shutter speed gear wheel. It was pressing against the inner part of plastic aperture ring coupling, only in contact when screwed down tight and barely any friction, but enough to make the ring stick or slow to return. Bent back and fixed.
Since I fixed two things why not a third? Grabbed my new (used and abused) 28mm f2. Was shooting a test roll with it, but the sticking aperture was driving me crazy, stuck at f16 and now at f11 too when stopped down, but fine again if manually turned. For example when using dof preview at f16 or f11 it would stay dark and stuck at that aperture until a wider aperture was selected. Disassembled, turns out someone worked on this lens as well in the past, was marked with red sharpie on screws. Took off mount, and determined it was with the return lever and not sticking blades. Thought maybe it was a worn spring, as it looked fairly clean. Decided to check If i could swap it from another lens. Took apart a snappy 135mm But it didnt use a coil spring. Took apart a teleconverter, but those were too long. Disassembled mount for better evaluation, almost lost the long spring on the carpet. The Dof preview lever was slightly bent causing friction as well as a bit of dirt on the black inner lever guide ring. the small Dof button would also get jammed if pushed too inward. Cleaned surfaces with naphtha and bent dof lever arm back and reassembled. Removed a deteriorating black rubber bumper, but no replacement to reinstall. Works fine without if, but longterm maybe not as it's metal on metal. Works snappier now and no more sticking.