Heard the same story last year at Louisville. Bought at set of concaves and grates for my 2588. Was on the edge with rotor loss in soybeans. Was on the phone numerous times with Kuchar trying to help my problem. Thought maybe it was just the year. Then started corn. Couldn't keep it in the rotor. Had all veins retarded over the concaves and grates and still was blowing corn all over the ground. Tried all concave settings and rotor speeds and couldn't keep the corn in. Rotor loss determined my ground speed. This wasn't just in one variety or one field. Was in numerous fields and varieties. Honestly tried to give them a fair shake. Finally stopped the combine in the middle of the day and put the OEM large wire concaves and keystock grates back in. Problem solved! Ended up sending them back. They might work better for someone else, but I had a bad year with them. I will compliment Kuchar on trying to help me out, but just coulnd't get it done.
Good luck!
Good luck!