Went to the farm to pull the pto shaft off the 660 having been unable to engage pto when hooked to bush hog. Disconnected the bush hog and just for kicks tried the pto lever, and it engaged without a problem. Hooked up the bush hog and got 10 acres cut. What might explain why it would not engage with the bush hog shaft attached but would when not? Could the weight of the bush hog shaft coupled with some bearing play cause just enough misalignment at the front end of the pto shaft to cause this? I will pull the pto shaft and replace bearing etc but relieved to have fodder mowed and ready for corn and bean planting.