Hi, I have a pentair minimax plus 400 that heats both a pool and a spa. The problem is the heater does not turn off when spa or pool get to set temperature. Heater has to be turned off manually. I replaced the thermal sensor, the two hi limit switches and the thermal fuse. All seemed to be ok but I swapped them out anyway. Still will not turn off at temperature. My next guess is the thermostat board or the two potentiometers. The fact that both pool and spa are affected suggests that it's not the pots. Anyone have any suggestions before I buy a new board?