Gary,
i was having a similar issue with the gear on my big 40% Cessna 310. I found that the ramp for the uplock was a little gritty and a little too tight on the retraction slider bar. I cleaned up the corners of the side plates with a file to put a sligjt chamfer on the inside surfaces and then polished the riding surfaces on the side plates a dremel and some metal polish. That helped immensely in smoothing them out.
as for the slamming down, i would recommend one of these on each up line:
Tailonz Pneumatic SCF-5/32 Air Flow Control Valve with Push-to-Connect Fitting, in-Line Speed Controller Union Straight - 5/32 Inch Tube OD x 5/32 Inch Tube OD （Pack of 5）
they are setup so they provide a restriction with flow in one direction and no restriction for flow in the opposite direction.
that will allow you to slow down the air leaving the cylinders when going down (you restrict the up line airflow) while getting full slow when going up.
as for them not making its way up. I would recommend one of the hi-flow retract valves. I designed and 3D printed my own and its amazing how much of a difference a valve designed for hi-flow works compared to one with just bigger festo fittings.