Thanks for the input, everyone.

BA and Maren: Yes, I think the flow rate is too high. It would seem the PO used to use these ShurFlo pumps and probably decided to go through them instead of buying a good pump.

After looking all of this up today, I've got my eye on these:

MARCH - SERIES 893



The March pumps are rated at 55,000 hours continuous use and have brushless DC motors with magnet drive (no seals to wear out). They seem to be the right choice. Also, using 1 amp, (instead of 4-5! of a ShurFlo), my electrical problems are SOLVED!

I guess the pump breaking was a blessing in disguise!