I assume that since you rebuilt the PV, you would have spotted any stripped gears in the cylinder head? To inspect the plastic drive gear shown
HERE you just need to remove the right side cover. It is not necessary to remove the clutch. Just be sure that if you remove the "claw" gear to get the cover off that you remember it's a left handed nut and the KIPS shaft needs to be supported like
THIS . As to sticking, the right side subvalve rod has a small O-ring on it. If the bore that this rod slides in is spooged, carboned up or just dirty then this o ring will cause a lot of drag and the PV action won't feel smooth. I put a lot of effort into making sure that hole is clean and smooth when I clean the PV's, then I coat the rod with some anti-seize and the action is a lot better.