"24V DC Cooling Fan" blades "eccentric" Fault solution is to try to install a solid fan so shake it up; Another method is to place the fan bearing grease on the shock cushion, thus weakening the noise. The first two methods do not resolve the substantive issues; last approach: the "24V DC Cooling Fan" fan removed, use a thin line across the center of the hole to lift the fan blades, if one end of the decline, indicating the end of a more sedate is available on the grinding wheel a few times, so a few times, and then thread lift "24V DC Cooling Fan" when the fan, if the fan can still in a horizontal position.