1. One of the three switch lights is off, and the internal contact is poor (fastening the wiring), the switch light is damaged (replacing the switch light), and the corresponding electric heating tube is damaged (beyond repair).

2. The switch lights are completely off or not heated, and the internal contact is poor (fastening wiring), the main thermostat (flashing thermostat) is damaged (replacing the debugging thermostat), the socket is damaged (replacing the special socket), and the power cord is damaged (replacing the special power cord).