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.
Have them in my 7010... work great. Had the front set only in 07' to help with hairpinning trash on the front right module, and this past harvest we bought the back half to complete the entire Kuchar set and got along fantastic. All the guys around here that run corn bean 70-8010's have switched over to these concaves and grates. Don't know anyone who has them in a 23-2588 though.
PS we are running the ST Rotor which is harder to keep corn in the machine... adding the kuchars into the back of the rotor virtually eliminated our struggles with rotor loss.
have heard better results with Kuchar on JD than CIH we make our own round bar concaves for the 30" and 24" rotors with smaller spacings between the bars for less fall through of cobs and use in soybeans. these help dramatically with rotor loss and plugging in the concaves. The round bars for the `10`s and `20`s we leave alone,seem fine. Have made many now really catching on. Kuchar looked alright seemed a little pricey.