The GFCI *breaker* (not an outlet) only goes to the pool (about 100' directly from panel to equipment pad). Whats odd is that I havent dug, drilled, etc. anywhere near it. I agree that its probably a leak somewhere, but the 2 ends of the wire that I can see are fine (circuit panel end and equipment pad end).

To throw another wrench into the works, I re-installed the receptacle (the same one that tripped the breaker last night) and now not only does it not trip the breaker, I was able to plug the pump into it and the pump is running fine off the outlet.

Unfortunately Im not 100% sure this cures anything. Considering I thought this issue was fixed last year, short of re-running the whole circuit, how is there any way to be sure? Im hoping I just need to replace/re-wire an outlet every year or two, but that doesnt make sense (why didnt the pump run when connected directly to the wires feeding the outlet that now mysteriously works?)

-Chris