Pull the fiberglass shroud off of the edge of the rotary screen door and then unbolt the rotary screen wheel itself (one bolt through center). Check to see if the paint is worn off from the brush seal all the way around. Some of the rotary screens are not square to the combine and the bush seal does not contact all the way around. If the brush is not contacting all the way around it will allow chaff to enter under the brush. To correct slightly bend which ever one of the four support bars is out of align to bring the wheel back into square with the door. Also blow the brush seal out real well while you have it off as they usually are stiff with dirt. Hope this helps.