The crop we are threshing is a type of grass that is tough to put through the combine compared to almost all other crops. But I do not feel that toughness to thresh should have a bearing on how the combine distributes the material to the chopper. We also use a 2388 with an after market chopper (Redecop) installed on it that seems to work fine. In fact both combines have basically the same chopper because the 9750 has a Redecop rotor in its chopper. The difference is in how the combines feed material to their choppers. The concave setting on the 9750 was 15 on the digital readout in the cab. How would concave gap affect which side of the chopper material went to IJ I appreciate your comments and questions and look forward to more as the dealer is baffled.