Only one that have given me trouble were usually dirty or some thing from people letting the slide off in the dirt. I tie the ujoints to the equipment so they don't slide in the dirt, keep the latch, tractor, and pto shaft clean, and pour oil on them like a high lift jack. They slide on pretty smooth.
The batwing is the heaviest to maneuver but it has a bracket that holds the shaft up above the tongue. That bracket leans forward and back. After I hook the shredder to the tractor (pin and hydraulics) I grab the bracket with my right hand and the joints with my left. When you pull on the bracket with your right hand the shaft moves toward the tractor. If it's not lined up I spin the ujoints with my left hand (best if wings are down already) and pull on the bracket with my right hand. The shredder shaft will slide on a little ways with the latch not pulled back. No sue trying to oull the latch back if your not lined up. Once the shafts are lined up keep pressure with you right hand and slide the latch back with your left hand. It slides right on.
IMO people screw up by trying to pull the latch back at the same time when they are trying to stab the pto shaft to the tractor.
Never do it with 2 people. Your asking for pinched fingers and POed people.