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I hope someone can give me some advice. I recently bought a new tub and gave my old 93 Hotspring Prodigy to my brother. He recently started having a problem controlling the temperature on the Prodigy. I installed a new thermostat last year and my brother recently put in a new heater element to replace the original which didn't survive the move.

After the new heater element was installed, the tub was working fine for a while, but now, if he turns the heat up to its normal setting (5 to 6 on the dial), the heat stops working. If he leaves it at 1 or 2 on the dial, it heats to about 85 or 90 degrees but no higher.

I took a look on the net and think it could be the "Spa High Limit control" or the "Heater High Limit control" but don't know which. I have read that if the "Spa High Limit control" fails, it trips the breaker for the tub, which is not happening. But I also read that if the "Heater High Limit" is bad, it should trip the heater. But that is not happening either. The tub just stops heating if the dial is set at its normal setting.

Any ideas or suggestions before I tell him to call the dealer?