I'm getting an OH on my 10 year old Leisure Bay spa with a Balboa spa pack. The spa doesn't actually seem to be over heating. I turned it down to 90, and it held the temp for a couple weeks with no OH. My guess was that it was the temp assembly and I ended up replacing it. The assembly has two sensors, one on the heater and one that takes the water temp. I replaced it with the OEM part from Rec Warehouse. Now I'm getting the OH just a few minutes after I power on or clear the OH. I watched the circuit board while it went into OH and there appears to be a spark when it kicks into OH. The spark appeared to be near a contact on the board labeled "high limit". Can anyone provide any help with this? I'm really hoping I don't have to replace the circuit board or the whole spa pack.