First of all, confirm whether the bearing is short of oil. Remove the fan cover in turn, remove the screw that fixes the motor cover at the front end, remove the shake head control button, remove the cover, drop some lubricating oil on the sliding bearings at both ends of the shaft, and try to rotate the shaft. If there is no obvious resistance, the problem will be solved. If it still doesn't move or the resistance is great, it is the rotor that sweeps the hole. Poor quality fans or poorly kept fans are more likely to sweep holes. The solution is to take out the rotor and polish the rust spots on the rotor and stator with 120 mesh fine sandpaper. If you can see obvious wear marks, you should operate carefully and slowly, and be careful not to break the coil wire or damage the enameled wire. It is good to resume installation after completion.