This is a lubrication problem. The old grease and oil has gotten
sticky. Flush out the gripper housing, where the trunion pistons go in
and out, with WD-40. use caution, cover the records, WD-40 will burn
holes in them. Let the mech go tnrough it's motions, adding more WD-40
as it runs. After a few cycles it will smooth out and work properly.
Squirt some between the gears to flush out any old grease binding
there. Rarely do you need to dis-assemble the mech to clear this
problem. Afterwards, if you want to re-lube the mech, I reccomend a
synthetic oil, like Mobil 1, they won't turn to varnish when they get
old.
Charlie Maier