Get another FAN. like putting a bent wheel on the car it will wobble, vibrate and take out the bearing. If the bearing was bad the shaft would slow down and the belts would keep twisting the hub fan assembly loosening up the hub. Over tightening the belts will damage the bearings in the water pump and alternator. Dirt in the fan pulley will cause an out of balance condition also antifreeze can get by the seal and into the water punp bearing causing the bearing to fail