First, aim the bimetal at the fulcrum of the switch, and then put the spring coil on the hook in front, with the open end facing the switch seat and the side without opening in front hanging on the hook in front of the switch button. Then press the button to try. If you feel elastic and can keep opening and closing, it's basically ok. Then try boiling water to see if it can trip after boiling. If it doesn't jump after boiling for 1~2 minutes, it means that the bimetal is in the wrong position, and then reinstall it.