Same problem, I took it apart and found that the thermostat had failed, there are "points" burnt out (like in older cars distributors) that make contact at the thermostat and there were some solder joints which had come loose as well, adding up to no contact through the "hot" side of the wiring. Basically it's not something you can repair, just go buy a new heater, they're about $30. If you decide to try to fix it, beware, it might be dangerous if you don't do everything exactly right, also beware that parts might cost more than the heater.