Waste,

Thanks for the encouraging advice. I have located the set of three hi-limit switches on the owners manual schematic. I also learned that I have a two-year warranty, so I think I'll take the easy route and call the PB tomorrow to get the warranty service. Beats breaking something else and having to get a new heater.

If the problem continues to reccur after the warranty expires, I'll be asking more questions in the forum.