Mamiya 645 Pro Frame Spacing / Film Advance Fix

When I got my Mamiya 645 Pro TL kit, both 120/220 film backs would advance the film too far between exposures. As a result, the frames were spaced too far apart on the roll and I was getting 5-6 exposures per roll of 120 film instead of the expected 15.

After many hours of troubleshooting, I figured out a simple fix (loosening the counter return spring) that fixed both of my film backs, which have since functioned perfectly through over 100 rolls of 120/220 film.

I know this fix doesn't address the root cause of the issue. The real problem is not that the counter return spring is too tight, but that resistance has increased somewhere else in the system. But this fix is simple and effective enough that I decided to make a video in case it can help other owners of defective 120/220 film backs for the Mamiya 645 Pro + Pro TL.

00:00 Introduction - Issue description
00:34 Disassembly
01:55 Counter return spring adjustment
03:07 Testing the fix
04:36 Reassembly
05:44 Outro