I've got a 9600 that's making a vibration that seems to be tied to the variable speed on the cylinder. I don't notice it at slow speeds on the high or low end but when I increase the cylinder speed it progressivly gets worse and worse. I've checked all bearings and everything seems to be lined up correctly with the cylinder but it seems like a u-joint in the main drive line under the hopper or a bent shaft from the gear box behind the cab but we've checked the u-joints and we're stumped. Several mechanics have seen the mystery vibration in other machines but have had no luck in finding the culprit. Any help would be much appreciated.