Something else to try Jan. Take the pump basket lid off and stand by with a couple big buckets of water. Turn on the pump, it will be dry, and pour the water into the chamber and see if the pump gobbles it up. Reason I say buckets and not a garden hose is you will need more volume than a hose can deliver. If it sucks the buckets up real quick then the impeller is probably OK. It really does sound like a suction side blockage. Reason the water got hot is it isn't moving and the energy just goes into churning thus heating the water in the chamber. I don't know what the pump configuration looks like and how easy it would be to disconnect the inlet to the pump. I'm thinking of jury rigging your vacuum hose right into the pump and bypassing the skimmer and piping just to see if it pumps OK.
Al