Sundance Marin 850 - Do I Need A New Circuit Board?

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I have a '95 Sundance Marin 850 that came with the house. We did some maintenance on it when we moved in, including replacing the main pump, and overall it works well. However there is a sporadic problem that has me close to buying a new board, but I'm trying to be sure before I shell out the money. Basically what happens (sometimes) is turning the main pump to high speed, or the secondary pump on, will cause the tub to "reset." It acts as if power was cut and then turned back on. No errors display on the panel, just everything turns off and then powers back up again. We can go for weeks without this happening, other times it will happen every time. It seems worse in the colder winter months. The main pump never fails to run on low speed, and the heat always runs. I've done a lot of reading and the temperature sensor seems like a common failure point, but it sounds like that would show an error and shut the whole tub down. I've done some basic voltage testing and the board is getting proper voltage. A friend who knows electronics told me that some of the components on the board are essentially circuit breakers and his guess was that one or more of those are going bad and are particularly sensitive to cold temps, maybe have moisture in them. So I've been very close to just buying a board but thought I'd look for some expert opinion before I did so. Thanks for any input you might have.