We have a 9860 with a high torque reverser and we keep wearing out the cams inside the upper sheaves on the variable speed drive feederhouse. We've replaced the sheaves and the belt twice ourselves in less than 1500 acres and have had a john deere technician replace them once. We've replaced the bracket that the sheaves mount on twice. The sheaves get so hot while we're running that they make water sizzle and we don't run it over 650rpm. We put a full tube of grease inside the sheaves when we replace them and grease the sheaves 10 shots per zerk per day and we adjust the belt so the bottom speed is running 490-500 rpm. I am beginning to wonder if we have a problem on our head causing this. We're running a john deere 12row 36". We've replaced the cams, sheaves and spring on the reverser also