Doesn't run. Check whether switch is on. Check if fuse has blown. Then call a serviceman.
Runs slowly. Apply oil at oiling points. Examine drive belt and adjust tension. Check motor (see
motor, electric). Then call a serviceman.
Vibrates noisily. Make sure fan is securely mounted. Examine and if necessary replace vibration dampeners under it. If noise continues, call serviceman.
Fan blades loose. Make sure fan is positioned properly then tighten. You may need an Allen wrench of the proper size to do this.