It its the M998 A0 setup the squirrel cage is a pain to get off of the motor shaft, but take it off and check the motor sound with no load. My squirrel cage was a metal one.
If the motor is suspect, I'd replace it. Last winter, luckily while I was in the truck, mine seized up. The battery gauge went from green down to red once I heard a squeal and seize. I shut it off. That thing was drawing some serious amperage to move the battery gauge down that far. There was that nice burning electrical smell with only a second of being locked up. I would have been very sad to have the truck to have had a fire. Cold drive home with a high of -4 on the way home.