Well I think I found out the problem with one of the holders (only tested one so far). I did the flashlight thing in the dark with one of the holders in and it seems that if the holder isn't sitting perfctly along the top then light can creep in at the corner...for this holder. The exposed part of the negative for this holder was at the corner as well so I think thats the only leak...for that holder. I have the other holder which had the leaks along the top edge of the film, which means the leak should be coming from the bottom edge of the camera, so I'll test that one this evening and see if I can't correct it. Thanks for all the tips...hopefully I can correct the leaks and not have to toss the holders since 5x7 holders aren't easy to come by.