I have a Coleman 550 with a pump problem. Pump 1 will not turn on low speed. It turns on high speed everytime I turn it on or the heater turns on. This causes the tub to overheat. It went up to 108 before I turned it off. Does this mean the pump is bad or is there some type of sensor to have it turn on high or low speed. Does anyone know if it is the pump, how difficult it would be to replace. Any help would be appreciated.