I have a 25 yr old Sweeney feeder that has one small damp clumping spot right under the lid handle bolt top center, I just haven't got around to sealing it with some industrial polyurethane sealant, the clumps never made it to the motor but did block the rest of the feed from getting to the fan for a small period of time.

All the really good ideas I've ever had came to me while I was milking a cow.