There may be a lubrication problem. In the off state, move the fan blades by hand. If it is difficult to turn, it is a lubrication problem: disassemble the fan, find the engine oil port, add lubricating oil and rotate the engine shaft. at the same time. This can usually be resolved. In a few cases, this is because the bearing is damaged and it is not practical to replace it.
It is also possible that the motor start capacitor is damaged. In this case, use something to move the fan blades when first turning on the fan, and the fan will start to spin. If there is a problem with the capacitor, you can easily find the capacitor by disassembling the fan switch position. It is usually a small black square with two wires. Buy one of the same model and replace-THE.