No hot water! The lower element in the water heater measures about 15 ohms and the upper one almost infinity, so that tells me the upper is a gonner. I think I need to drain the tank to below the upper element, unscrew it, and screw in another. Is it that simple? Will the lower element continue to work with the upper disconnected? If not, can I do something to make this happen? My school teacher wife needs a morning shower! HELP!