You may only need to adjust your rotor speed. We had that problem in corn a couple years ago because we were overloading one side of the sieve. Increased rotor speed 50RPM and it changed the grain distribution on the sieve and no more problem.To check sieve hit brake hard, pull throttle to off and push hydrostat full ahead all at the same time. Do this while harvesting at normal speed and the combine will stop dead in it's tracks.This was recommended to me by the Case combine rep. Now you can check grain pattern on sieve, tailings volume, if there is grain in straw at back of rotor, etc., etc. Works great. Good luck.