I just bought a really mint condition Canon T90 with a bunch of Canon FD lenses. The lenses work properly on my AE-1, so I know they are OK. But the T90 won't shoot at all. The film loads, the counter shows number 1, the battery check is OK, the LCD window shows all the functions, etc. Each time the back door is opened and closed the film advances to number 1. I pushed the rewind switch inside the control panel; nothing. The shutter curtains appear perfect. The depth-of-field works. The mirror remains down and the shutter release button seems to make contact ok, but the mirror doesn't fly up and the shutter remains closed. The self-timer counts down OK, but still no shutter release. The mirror is not stuck, because I can gently lift it from the bottom with my fingertip. Oh, one more thing: the film sprocket/roller near the take-up side is freewheeling all the time. Any suggestions before I send it to a repair service?