In regards to your leaking cylinder, I thought I had one leaking, but found that one of the lines wasn't tight, tightened and stopped my leaking. Just something you might want to check.
I think someone on this or the other forum did get a cylinder rebuilt, but Lippert just does a remove and replace.
Michelle & Ann
2018 Chevy 3500HD Crew Cab High Country DRW, D/A, 2016 RW39MB, Dual ACs, Auto Level, Auto Sat Dish, Stack W/D, King Sleep #, 17.5" Sailuns w/Disc, MORryde IS & Pin, Comfort Ride Hitch, 5.5 Onan, Res Fridge & Induction Cook Top