Hello, I got an AE-1 from ebay a while ago that was advertised as working. I've been trying to get it to work since then, but had no success. The problem is as following: When I set the camera to a really slow shutter speed like 1s everything works perfectly, but when I set it to shutter speeds 1/15 and up, the shutter doesn't open. The mirror flips up and down for the right amount of time, but the curtain doesn't open. The only working speeds are from bulb to 1/8, which are quite useless for me. Battery is new. Does somebody have any ideas? Thank you. Tim