On all AF combines the front side of the clean grain chain has 2 blocks of wood to keep the whip out of it. There is a new kit that is a "roller" to install. I believe the part number is 87298638. I have it installed on a 1660 works wonderful.
Now here is something. I looked under the shield on a 2588 new combine today and they still install the old wood blocks.
Thought by now it would have the roller. JWK