No, the bearing itself. I have no fan attached, using an electrical. One of the four threaded bolt holes sheared off at some point. When I pulled the cover off for inspection of timing last week, the bolt was basically just hanging on. I decided to leave that bolt out because I could imagine it flying off at some point... well, the pulley is now out of balance and the bearing is being eaten alive. I could "glue" the bolt back in to rebalance it, it does diminish the sound, but you can still tell that the pulley is making noise.