Replaced a shutter on an old Pentax and now the mirror sticks

I swapped the shutter unit on a Pentax MX last week, using a donor part from a scrap body. The curtain speeds are fine, but now the mirror locks up about one in every five shots. I had to remove the mirror box to get to the shutter, so I'm guessing I messed up the timing or the mirror return spring when I put it back. The whole job took me about three hours. Has anyone run into this after a shutter swap on a similar SLR, and is there a specific adjustment I should look at first?

3 comments

3 Comments

angelam803d ago

Check the foam mirror bumper, it might be totally rotten and sticking to the mirror after you fire it. That old foam turns to glue and would cause exactly that random lock up. Cameron_hernandez69 is right about the small parts causing big problems, and a perished bumper is a classic one people miss. If it's gunked up, cleaning it and putting in a new foam piece is way easier than messing with the governor spring again.

theajohnson3d ago

Honestly, that sounds like the mirror governor got knocked out of whack when you pulled the box. Tbh, I'd check that little spring and lever assembly first, it's easy to misalign.

cameron_hernandez693d ago

Ugh, that's so true. It's like when one tiny thing gets bumped and the whole system goes weird. Always the smallest part causing the biggest headache.