Last weekend, I returned home from a trip and found my pump circuit breaker tripped and the relay not working (doesn't switch, test button stuck in the down position). I ordered a new one and in the interim moved a relay of the same model from another circuit. Everything seemed to be working fine. Now, after having been away for a week, the exact same thing has happened, so it seems something is killing my relay. Pump is a Pentair Whisperflo. My understanding is that this model does not have a centrifugal switch. Any ideas?