Greetings: I have a 40 gal electric hot water heater which will not shut off. I have replaced both elements and thermostats and have the lower thermostat cycling properly, but the upper continues to stay on continuously. I have actually replaced the upper with three different units, each from a different manufacturer and still no cycling. I have bench tested each of the three thermostats on my electric range and they turn off (break connection) when heated and close (make connection) when I cool them off. How is this possible with a mechanical, snap-switch device?Thanks!Larry