I got a very loud knocked noise from what seems to be around the top of the belt cover, where the air tube mounts to. Right in that area there is these 3 rectangle blades/fins that are about 3 inches longand about 3/4 inch high. If i push on one of them, the noise goes away. Its like whatever is on the other side of it is rubbing against something internal. I took the belt cover off and didn’t see anything abnormal. Any ideas?