Combines 9720 grain loss

I assume you have the deflectors under the rotor on the right side and you have adjusted them to center the material bacck over the chafferIJ Also what rotor speed are you runningIJ I would try to run as slow as possible while still getting all the kernals off the cob.

Eksactly my words, run the rotor as slow as possible. It is better to tighten the concave a little than speeding up the rotor.