Originally Posted by Dave9
Sometimes the windings just short out, given enough heat and time, but I would have tried cleaning up the commutator including the grooves as WobblyElvis mentioned, and degunking the whole thing, and lubing the bearings (I mean if sleeve bushings). That Denso made in Japan was probably as good as it gets, I wouldn't expect similar life from a TYC in the same conditions but you do what you have to...
I problem I had was getting the case apart without damaging the connector, I needed to take dikes to the plastic. Back in 1998 I was able to repair a condenser fan motor by changing out the $5 bearing. They did not have aftermarket motors back then. I just needed to peak inside.