I own a Sta-Rite max-e-therm heater model SR333NA. It was purchased 5 years ago. Recently the heater quit working. Any time the temperature is set to higher than the current water temperature, the "Service System" led light comes on. The troubleshooting guide indicates that this is an issue with the water flow and/or the water pressure switch. The water flow is fine and filters all clean. I removed and tested the pressure switch and it seems to work correctly (with the switch closed the contacts read 0 ohms). I temporarily connected the two pressure switch wires together and the "Service System" led light still comes on whenever the temp is set to higher than current. I even verified that the wiring going into the control board is fine and the "temporarily shorted" wires are showing at that end correctly. Also the "PS" led on the control board comes on at the same time as the "Service System" indicator comes on. My question is if there is nothing wrong with the water flow and there is nothing wrong with the switch or the wiring to the control board, what else can be causing the "Service System" and "PS" led to turn on? Do I have a bad control board?