If you can't tell what accesory it is comming from, get a dowel or broom handle 2-3 ft long. With the enging running, and without getting the dowel wrapped in the belt or smacked by the fan, place one end of the dowel on the accesory or it's mount. Then cup your ear to the other end of your dowel. The accesory that the noise is comming from will be noticeably louder.