We have a 6 year 5 month old Kenmore Power Miser 12 electric water heater that is now tripping the thermostat reset button and turning itself off. It has happened occasionally in the past (3 or 4 times since installation), but now has shut off 3 times in the past week. The unit has a "self-cleaning Roto-Swirl" cold water inlet tube (whatever that does). Do I have a major problem developing or something minor that I can do something about? This seems to be something to do with the High Temperature shut off system. I've never drained the unit or done anything to it except adjust the temp. on the hi & low thermo-stat which is now set about 125 degrees.