Andrew,

Yes, the 8 shots were all the same density and the lens was not on A. I tried what you said about opening the back of the camera and using a slow shutter speed. Sure enough, all of the aperture positions were doing nothing and the lens was stuck wide open! I pulled it off, fooled around with it a touch and put it back on, and now it's working fine. Weirdest thing.

Thanks for your time!

Robert