Hmm. I wonder if the seal across the hinge part of the back is gone/deteriorated? (#3 in this shot)
I think the leak is stronger toward the right side, viewing the camera from the back when the film is upside down -- but it could just mean the sun was on that side!
These things can be weird, the actual leak may be near the supply or take-up spool and not striking the actual mask frame area. In such a case, it's either the frame before, or the frame after the shot that gets light struck. My hands-on personal experience with these problems is still fairly limited (thank the Flying Spaghetti Monster!) so it's difficult to speculate on the full range of possibilities.
Another dubious thought is that possibly the light baffle behind the mirror in the body isn't closing all the way, and light comes in through the lens and around the sides of the mirror. As I type that it sounds far fetched, but obviously something is not in factory spec.
An additional vague possibility (based on analysis, not experience! ) is that the back isn't seating tightly due to the little retaining hooks being worn or loose or something.
I suppose black (gaffers') tape could be carefully applied to help in isolating the light path. If all the back attachment and closure stuff is taped and it still happens, that might suggest the light baffle. If the joint between the back and the body is taped and you still get it, it pretty much has to be one of the long seals at the top or bottom.
You could also plan some real test cases -- put the camera in the sun with a lens cap on and pretend to do some exposures, change the angle of the light hitting it, etc.
That's what passes for my thinking -- no charge!
Last edited by DWThomas; 06-28-2013 at 04:56 PM. Click to view previous post history.