I’m losing water in my pool ~1” overnight (~6-8 hrs) and I think I have it pinpointed to the control valve on the sand filter. I have a Hayward Pro Series Model S244T and when its in filter mode, I have water leaking by the control valve and out the wastewater line. My question is, do I need to replace the entire control valve or can I replace a seal/o-ring within the head?