We are also experiencing excessive rotor loss and I am not sure what to do about it either. We are combining 180 bu corn. I have tried everyhing I can think of on our R72. It is fully hyperized. I have installed the new style high wire seperater grate. Have the half hieght bars, reverse bar mounted in the seperator grate. I am contemplating putting in some reverse bars on the rotor to see if that will help. I have tried the rotor speed from 250 to 350 and that doesn't seem to make any difference. Concave from 8 to 12 on the scale. I get the best results at 350 and the concave set at 10, but it still isn't as good as it should be.