I have a Super MTA diesel. I put a different pto unit on the tractor. Old one had several bearings worn. Too much play in the shaft. I put different unit in, adjusted bands according to the manual and filled it with oil. I checked to make sure it worked and nothing happened. I checked seasonal disconnect and it seemed to be in the on position. I then took cover off underneath the main clutch. When I removed cover, a rivet head came out. Also, when pto handle is in the middle position,I can turn the shaft in the middle of clutch disc. I checked our other mta and that one did not do that. Can someone give some insight into this? Are there splines that could be stripped. Any advice would be appreciated. Thanks