I have a ’99 Altamar Model 850. I just opened it for the summer and I have been getting a “FLO” notation since as follows: Pump 1 running at Hi or Lo, no FLO indication and heater works and flow switch visibly is closed. Pump 2 running have FLO indication and flow switch is open and finally with both pumps one and two off and temperature set above actual water temp there if a FLO indication, the flow switch is open and the heater does not come on. Is this an indication of a circulation pump failure? All other features seem to function normally.