In starting up our dormant hot tub this fall, the breaker popped immediately each time I tried. OMG How many $$$$$ am I going to be out when I call the repair guy. I relied on my inflated sense of handiness and decided to diagnose and (is it possible?) repair the problem. Since we have a quite new pump motor (Which I waaaay overpaid for through our spa repair guy - what a sap I was), I thought it might be the entire circuit board/heater unit which is nearly a thousand bucks even if I were to do it myself. I then noted inside the circuit cover that the heater tube seemed to be held on by only two nuts and the nuts on the flat copper contacts (plus the threaded plumbing fittings on the 'in' and 'out' PVC pipes). I took the heater tube out, flipped the breaker back on (only for a few moments) and IT DIDN'T POP!!! Diagnoses: Bad heater tube. Found it online at the Hot Tub Warehouse for around $120... put it in rather easily... and VOILA!!! ...Repaired! Works perfectly. I feel like I'm the King of that thing!