So for a while I've been trying to figure out why I'm getting this strange line across the top of the frame with my Canon AV1. I can see the line on the negative itself, so it can't be my scanner. It's probably worth mentioning that the line doesn't go into the space between the frames. I use the lens (50mm 1.8) on my FTb all the time and it works fine, so it can't be that either. I've cleaned out the parts of the camera that come into contact with the film and removed any dust or debris from the film door etc. I've noticed that when it happens, it's always at 1/1000 shutter speed. Shutter speeds are accurate, but it does have a slight 'cough' every now and then. If anyone has any ideas that I haven't yet thought of, or any guidance on the cough please share your knowledge!! It's a great camera and would be a shame to retire it, but I just can't figure out this issue. Thanks in advance!