I have a Pentair Easy touch 8 which if set for 80 degrees will trigger the heater, heater runs gets water to 80 and then reading on panel will bounce to 79 and back to 80 very quickly. Recently I had SPA temp set for 100, I watched the temp get to 100, it stayed on 100 for about 10 seconds and then went back to 99 then 2 min later temp bounced to 101. I have changed the temp sensor but same issue is occurring. Anyone have ideas what's going on here? Do I have a bad sensor or maybe motherboard?