Teac Receiver lost AM and FM
Well, if your unit had that happen, it sounds like it is possible. ;)
I would imagine that the radio, like all the other inputs, is in itself a separate unit or circuit board. If something fails on it, it probably wouldn't harm other inputs or the actual amplification itself... just a guess on my but it makes sense. A repair shop could probably open up the case and visually inspect the tuner circuits to make sure there isn't a short or dead something somewhere.
If there is still sound in Jim's case, I would try a different antenna and/or make sure its hooked into the correct antenna hookup. if sound but antenna change doesnt help, it could still be an internal but maybe simply problem.
i'm no pro but that's my 2cents