Is My Onkyo Receiver's Tuner Dead or Just Playing Posum?

Tried using the AM/FM tuner in my Onkyo TX-SR876 home theater receiver but getting no sound. I called Onkyo tech support but the best they could tell me is: "Try a different antenna". This tuner has worked in the past (Las Vegas) but I had a clean line-of-sight to Black Mountain broadcasting antennas. I know this is a shot in the dark but maybe an Onkyo wizard will read and suggest a fix? Can't believe the tuner would just konk out...