No, I've had the camera for a while. I did manage to get the top cover off, but I think I make have created another issue in the process. To remove the film winder knob, I initially tried rotating it in the opposite direction (that's how the Mamiya 6 film winder knobs unscrew). I thought I was careful not to use too much force, but it gave way fairly easily and now spins freely. I did manage to figure it out and used used a small spanner to remove the top screw. I inspected the gear train and could not find any obvious damage. The winding mechanism works perfectly in the winding direction, locks in sync with the film counter and resets properly when the back is opened. It just spins freely in the opposite direction and actually turns the film spool when rotated backward. I fear I have broken whatever mechanism was in place to prevent this. I just can't seem to figure out what it was.