My SWG is 11 years old and I replaced the cell 3 years ago. This year, when I turn it on, I immediately get the solid red light "insufficient water flow". I cleaned the cell with acid and it looks good. I checked the wires (visual inspection) going the the flow sensor and they look good. The pressure in the filter is 12psi which is normal. There are no air bubbles in my pump basket. I am guessing it's either the flow sensor or the board inside the unit the the sensor is attached to. Anything else I can try before ordering a new sensor?