Rich Heimlich wrote:
I have two fans that have stopped working and both of them cost enough
that I'm thinking of having a go at repairing them. The key question
is, when a fan burns out, what generally is the problem and is it
easily repairable? Power is still getting to the fan. It just isn't
turning any longer.

I have several $15 or $20 "two motor" fans which go into double
hung windows up to 30 inches wide. They accumulate enough crud
in the motors and blades that I take the motors apart every
spring and drop some oil on the bushings. It would probably be
simply to toss them and buy new ones, but I am retired and need
to find things to do.