Hehe, that's me, thanks for the compliment. The one seal area that doesn't cover is the dark slide -- mostly because I have yet to be forced to open that up! I now have four backs, I guess I could risk getting out a screwdriver, except I think I need to splurge on some of the 'official' JIS flavors.
Originally Posted by Daire Quinlan
I am still a bit uncertain about this leak analysis. If the orientation of the original photo is as the scene looks in the OP (my original assumption), the image on film is upside down and reversed right to left, putting the leak on the side away from the dark slide suggesting a hinge seal problem (unless the camera was used upside down!!!)
That appears to be a fairly mild leak which makes it more difficult to track down. In general the degree of effect of leaks can vary with the orientation of the camera, ambient light intensity and how quickly one winds to the next frame. On the roll that led to the "Oh my back!" photo on that page of mine, the first frame was fine, as the film was loaded in the house in relatively subdued light and wound to the first frame. The leak was hitting the film between the supply spool and the roller; it was the subsequent frame where all hell let loose.
One suspects there is a repair manual for backs that might show what Bronica thought should be there seal-wise, but I've never found one.