I just a bought a 2005 new holland TC29da with 600 hundred hours, I made sure everything worked when I bought it. I made sure the PTO would turn on but the seller didn't have anything to out a load on the PTO. I just a bought a used 72inch finish mower. When I tried to engage the PTO the PTO would only grind and not engage. I made sure to push the clutch in every time but still would only grind. Any thoughts on what it could be?