RE: Weird UP-3 valve problem
Could also be bleed-thru of the retract cylinder from one side to the other .. try some of the magic bvm thin lube .. inject in the airlines at the retract on both sides, and cycle it a bit. I've seen a few cases where a nosegear on a Kingcat did this for the first few cycles after sitting for a while .. cycle a few times with manual assist on the retraction and it's fine.
Dave