/diy/ - Do It Yourself

Long story short the main blower fan isn't running. If I give it a push when it tries to kick in during the heating cycle then it will start and run so I suspect the starting capacitor, BUT it doesn't stay running for the full cycle. In the middle of the cycle I can hear and see it change speed and then it jams completely near the end of the cycle. I can't get it started afterwards no matter how much I push and it feels like I'm fighting the magnetic field. However, It will start again and sometimes by itself if I cut power to the furnace for like 30 seconds; if it's any less than 30 seconds then it stays jammed and can't be started by pushing.

Thoughts on what could be wrong? Reading over my own description I'm starting to think bad insulation on the motor winding that doesn't show until the motor heats up, but a single short causing the motor to not run at all seems unlikely to me.