Brian Moore
Moderator
Normally I'd be looking through the open back and watching what's happening with the shutter opening/closing while fiddling with levers and knobs. But you have put film in it. So,...take a picture of your eyeball. (Right or left,...whichever one is more accurate for close up viewing.) While taking the picture, use said eyeball to try to ascertain whether the shutter is active and whether in fact it is hanging open a long while.
Try with shutter at a faster speed, too. Slower speeds are more liable to hang up. (Although, for the period 1/100 wasn't slow.)
Try with shutter at a faster speed, too. Slower speeds are more liable to hang up. (Although, for the period 1/100 wasn't slow.)