My heater will only reach about 96 degrees inlet temp with either temp control knob set to max. If I turn the knob harder so I am past the end of the pot I can get it to relight but then it is in a non linear zone and it goes up to about 110 before shutting off. I have tried fiddling with the two pots on the back of the board which I have assumed are for trim but they have no detectable effect. How do I get the desired set point of 103 back into the range of the controls? Thoughts?