RB67 Pro S: Locked Wind Lever from Crumbled Seal and Spring
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
This Mamiya RB67 PRO S came into the shop locked up. The wind lever would not move. When removing one of the side covers, I found the situation as seen in photo two: a light seal that had dried up and crumbled into many pieces inside the camera mechanism.
The residue has traveled over the mirror gears and also it is very close to the mirror governor. If this mess were to get into the mirror governor (round part in center upper right of photo), it would cause the mirror to likely stop in its movement. The mirror governor slows down the mirror so that it does not slam to the upward position when released as this would crack the mirror. These governors do fail, the third photo shows a box of them that were removed from camera bodies.
In this case, the problem was actually caused by a small piece of a revolving back adapter spring. Photo four shows the mirror gear with the small part stuck in it as I found it when inspecting the mirror mechanism. Although I found the place that the broken part came from (photo five), a new part had already been installed. So, it seems like the piece had broken, worked its way into the camera body and then the part was replaced without finding the broken bit. I do understand how this would work as it would probably be assumed that the broken piece had fallen out of the revolving back and not made its way back into the camera body.
