My main om4t. I got a lens for it today and all of a sudden after mounting the aperture changes did not affect the meter. Meter only worked during stop down with the dof button. Ugh.
After some checking the old lens and then the body I figured out the aperture coupling lever in the body was not returning. Quick check on my computer made me realize my service manual wasn't saved when I had to reinstall my windows after a bad virus. Doh. Ugh.
Lucky I have a parts body that I have been using up to repair my two om4ts. So took the lens mount off and figured out how the aperture meter coupling worked as well as the shutter speed selector. Then stripped my user body to repair. Turns out the tensioned string that returns the aperture metering flange jumped its track a bit and there was some friction against the shutter speed selector gear flange. Got it all back together but still didn't work, had to go back and swap all three pieces of the mount, shutter speed ring, and speed gear flange. Finally worked, but i must have bumped the speed gear inside and speeds were off. Ugh. Again apart and adjusted and back again.
Success. Finally. 2hrs later lol.