If that doesn't work, then it probably needs either the contacts cleaned on the back (and the body), or a replacement back. That said, how much is this F5 going for, and what's the cosmetic condition? If it's scratched up, and above $300, it might be worth driving the 150 miles or so to Seattle and buying one of the two F5's at Glazer's Camera. I tried them both out before I bought mine on Friday, and the AF selection pad worked fine on both cameras. They are open today (Sunday) until 5 pm.

-J