Motor overheating, clean the cooling holes. The toaster motor will generate a certain amount of heat when working, in order to prevent excessive heat from damaging the motor, the bottom of the toaster is usually designed with heat dissipation holes. If these cooling holes are clogged with dough or dust, it will cause the toaster motor to overheat, making a humming sound and showing the fermentation state. When this happens, first check the state of the heat sink holes, then clear the blockage to make the heat sinks work properly, and then plug in and use the motor when its temperature drops.