I have a 8 year old nordic spa with gecko spa pack, the HL error symbol has come on and will not reset, I was informed that the high temp sensor might not working, but it is soldered right to board, I have been able to remove it, but no change, so the heater will not come on as it thinks the water is too hot, I have kept the spa pack in as I need the water circulating to keep from freezing, I live in Canada. Q. can I replace the high temp sensor only or is there other sensors I should be checking, the dealer says I have to replace entire circuit board, very expensive.