It's also possible to shoot shutter-priority (lens on "A") with a motor attached, but have something unknown wrong with the motor, which means all your shots are actually taken at the smallest aperture on the lens and totally underexposed (ask me how I know this.) If you have a new-to-you F-1N and motor combination, you might want to test this with the back open and make sure the aperture is changing wider and narrower as you change how much light you aim it at while firing it.

Assuming you've physically removed the battery and have it set to 1/60 or above and it still doesn't work, then I'd start looking at the usual suspects: mirror hanging up (due to sticky foam?), aperture preview lever engaged when lens was mounted, etc.

Duncan