I have had trouble solving rotor loss this fall in corn. This is on a 6088 with 8 row head. I've tried concave from 15-35, rotor speed from 250-450, ground speed from 3-5 mph. Rotor is set up with four straight bars over front half of grates and two straight bars plus four spike tooth rasp bars over back half of grates. Veins are fully retarded. Using round bar concaves and keystock grates. Corn is 25-35% and mostly 140-180 bushel although I have done some poorer corn that also gave trouble. Any ideas?