Combines F corn settings

Slow it down as much as possible, open up a touch wider, open sieves just a touch more and crank the fan up to all it will go. I have had problems for years with an F not handling soft cobs well. The K2 (long tail) will handle and clean soft cob corn much better.

You did not mention if you were running filler plates or not. I had this problem until I bought a used set and installed them.