Thanks for the great input Al.

I haven't pulled the cover yet. Today was a cooler day and the pump ran perfectly. I did inspect the pump and all the vents were clear, and there was good airflow around/through the vents. Given that the pump seems to be running just fine without any of the symptoms you mention, I think it's reasonable to replace the thermal switch and see what happens.

Any idea where I could find an exploded view of this pump? My old pool company provided no documentation when they installed this motor.