Combines overloaded shoe

pulling wires in thresher concave is good idea. Also closer grate setting will do more threshing on RH side. Worn helicals will cause this problem. Finally CHECK the FAN , there is a hydro charge filter that can seep and cause coating of the fan on the lH side. This will lower air blown on this rh side. Check the air choke as well, is it levelIJ Check splitter for obstructions and or bends. There are troughs available or can be made to move material via distribution augers (check them) to the R or l

What year R60IJ '90 and '91 had P3 cylinder setup. Maybe some proto's prior to '91. A little hyperizing should greatly reduce your problem.