I have a 2002 Viking Spa, The temp control is push buttons on the top of the unit. It has a dedicated 50A GFI Breaker approx 12 Feet from the tub. It has worked flawlessly for three years now. This spring, we emptied it for approx 1.5 months to clean it and just recently re-filled it and put it back into service.
It ran without issue for approximately 2 weeks. Then it tripped the breaker, not the GFI portion, but the breaker itself. I reset and it ran for a couple of days then tripped again. Then it would only run overnight, then hours, then minutes, and now it is down to immediately tripping the breaker.
I have never had any issues with it prior to this. The breaker is not getting warm, nor has it any of the other times.
After reading the posts here, I am curious about by heating element. However, like I said, after the re-fill, it brought the water up to temp with no issue and has run fine since until now. Ozonator maybe? Weak Breaker? Any help would be appreciated.

Disregard. After reading agin here how to test everything, I discovered my heater was bad. Great forum with a lot of info.