Filter pump: post-mortem

Well, I opened up the pump and found, first of all, quite a bit of
deformity of the impeller, likely due to heat. The (stainless?)
steel threads on the impeller were stripped clean. The threads on
the motor shaft were unharmed, no doubt due to the fact that it is
made from a harder metal. I suspect that the impeller siezed due to
the heat and the next weakest link in the chain failed - the impeller
threads. (so, indeed, "the pump is shot" ;-). I bought a
similarlarly-spec'ed Jacuzzi motor/pump to replace it and all is,
once again, right with the world!

Thanks for all your insight and suggestions.

-Mike