My driveline from my pto to flail mower has u joints on each end and has a spring plunger that snaps in place to hold the driveline on both the pto of the tractor and the flail mower. The problem I am having is the springs are not working on both ends and I have to slide the u joints onto the splines and then use a punch to punch out the plunger to lock them onto the splines. I have to keep checking them because they have a tendancy to come off the splines. There is cross braces on both the tractor and mower so the few times it has come off it did not hurt anyone. I looked at these plungers real close and see no way to remove them so they can be replaced. My question is, are they replacable or do I have to get new u joints? Is there a better way to go than the plunger type? I have seen the collar type that is spring loaded that snaps into place, are they better?