Hard to see where a SS AC Relay could hurt an induction motor if the
motor isn't overheating.

Does the fan still spin? Is there continuity in the winding?

John :-#)#

The motor still spins easily. There is no DC continuity from the power plug but I beleive this is normal for induction motors? Perhaps the overheat sensor has opened permenently. Home Depot gave me a replacement so I will try it again. These fans typically last for many years when plugged directly into a wall socket. This is a real mystery to me. Perhaps SS relays generate some large spikes on their output? I should check it with a scope.
Thanks for the comments.