S2a rocker/arm hangup?

something is hanging up. newly rebuilt engine. vacuum gauge reading ~5 instead of ~18psi. Pulled the head and dismantled valves, polished valve stems and they spin nicely in the guides. Rocker arms spin smoothly on new bushings but occasionlly catch and don't close. The cylinder head has been shaved 100 thousands. The cam is ETC 7128 pushrods are slightly shorter than the originals for this engine but spec for this cam. I've polished the sides of the rockers and washers and pedestals. Tappet clearance is 10-12 thousands. If anyone has an idea of what is wrong, please let me know. I really don't know what to do to correct this problem. Thank you.

This is fine to post by me.

I would look carefully at the pads where the rocker contacts the top of the valve stem.

If there's a wear lip on this oad, that could stop the rocker returning freely - especially if the rocker geometry has been changed a bit owing to the head skim.