The CSR kit will move the back axle back to give the chaffer more room to move. It also gives info on things to do to eliminate some other contact points, but when you buy the kit your pretty much sworn to secrecy not to give out all the details. The kit is worth it, it should help.
If your chaffer is breaking up, take off the concave inspection doors on the left side and look at the rear of the auger bed. It might be breaking up there too. We found lots of little cracks in our 2000 2388 when we put this kit in. Case also makes heavier arms for the chaffer frame and updated bearing supports. One last thing when we had it all pulled apart our machanic came out with a tool to align the two ecentrinc bearings and the bearing in the middle of the hexagon shaft. Its the shaft that drives the augers under the rotor. When we got this prperly aligned and the CSR kit in, a little welding on the auger bed, and new bushings the combine never ran smoother. Hope this helps, nothing more frustrating than going home to pull out the chaffer and weld a couple times a season.