I've torn this thing all the way down to the cassette mechanism and the service manual just refuses to acknowledge it's existence other than in passing and SOMEHOW I have to take this thing apart to verify in fact that one of the gears broke it's center section
help
ok well it turns out that gear with the busted center shaft is the encoder gear, with contacts on the back that presumably tell the camera what position the entire mechanism is in at all times. So this whole block needs to be replaced, because that gear isn't coming out without more disassembly that I'm not capable of. Poopy.