I had THE SAME PROBLEM with my jd420 re-powered with a kohler Command Pro CH740. I burnt up my clutch almost immediately. I just left the clutch off since I do not use the front PTO at all on that tractor. I did not use a kit for the re-power and the outfits that sell the new engines with kits would not sell t=me the proper washer. Tried to make my own washer but not successfully!