2001 Hot Springs Grandee in near perfect condition used daily. Again, tube is in excellent condition. Has been used daily since new. Have replaced normal stuff over years to include circ pump, main pump impellors, jets, etc... Recently main heater 30AMP GCFI has started tripping after hours or days. I cannot tell you exact circumstances that trip the GCFI. It seems always to happen when tub is open and jets are turned on (requiring heating mode). I have replaced IN ORDER : 30AMP GCFI , HEATING ELEMENT , HEATER PCB CONTROL BOARD This is a standard HOT SPRING setup so has subpanel with a 30AMP GCFI breaker for the heater and a 20AMP GCFI breaker for the tube pumps/control board. I have NOT used a meter to measure AMP draw of the heater yet. Just seems hard to believe new heater is bad. AND, of course, maybe new GCFI is bad also. ?!?! The tub acts normally when first turned on. Without running jets, the tub will heat up to EXAMPLE 102 within hours. But after several days heater GFI will be tripped. OR.... if you run tub jets with top open, GFI will trip. ALSO.... circulation pump appears normal and filters clean. I have the side "water-fall" option that lets you see the recirc pump water flow. Also, I do not get the HI-LIMIT flashing light and tub shut-down if recirc pump is low flow. QUESTION: I DO NOT FEEL the high heat flow out of the bottom vent of the tub like normal when you have jets running. Is the heater in these tubs ONE heat mode ? Off / ON. Or is there a HI / LOW mode? APPRECIATE THOUGHTS.