Oh, yeah - it's a mid-'80's 115V with S/N MIA that I've owned for 10 years without much trouble.
Okay, so the thing stops heating out of the blue and I do the usual troubleshooting. I think I found the pump not flowing well so took it apart to find a little crud (and, now, ice) but all was otherwise well. Reassembled and tested only to find cold water flowing out the port to the tub. Was making the amature mistake of testing for power to the pump and heater by placing my Wiggy across the leads to the ground spade and popping the GFI but eventually got it straight - 115 to both.
Got the heater apart, cleaned out some crud but otherwise it looks good and resists at about 8 ohms. Plug it in and it gets hot to the touch. Aaagggh! Now what? What am I missing? Possible bad overtemp kick-out? Naaaaah ... don't hear a relay and the reset was never tripped.
Just thinking in print at this poing so I'll shut up. SOS!!!