The cob should be going through the chopper, go and check if anything is
plugged up. Chopper in low speed, and knives fully back.

 

Are they plugged up. The cobs and such shouldn't be near the sieves. Is the beater grate missing. So they are not making it onto the walkers ?

 

Are they full cobs or pieces of cob. You may be over threshing and your pushing them through your concave. Or they are over threshed and falling through walkers and coming off your shaker pan.

If they are whole cobs, and they are piling on your sieves. Your beater grate may have fallin off the concave, or you have your chopper moved forward without having backstop installed. I have seen this done with milo stalks.

 

Figured it out the husk and the cob were not getting ground up by the cylinder and allowing them to overwhelm the walkes, spilling out the front of the walkers onto the pre cleaner and the sieve. Adjusted the concave and cylinder and no more problem.