"Has it been dropped or something heavy dropped on the deck? "

Doesn't have to be. If it uses those dry brass bearings they wear.

Some people plug their tape units into the switched outlet on their amp or receiver and just leave the power switch on. In that case the motor runs all the time. I have seen this on cassette decks as well and it actually happened to one of mine. Also like a Dual 1215 turntable that has no strobe, the linkage gums up and while it disengages the idler the motor still runs.