1. Check whether the fuse and power cord are damaged, whether the motor bearing is lubricated and whether the carbon brush is in contact.

2. In the process of maintenance, use a multimeter to find out the cause of the fault by measuring the voltage.

3. Fix the problem. If the bearing is too dry, add lubricating oil. If the carbon brush has poor contact, adjust the carbon brush.

4. If the governor has poor contact, it is necessary to repair or replace the motor winding, open the circuit, start from scratch or even replace the new motor.