2006 Rockshox Pike 454 Air U-turn Fix-up or Spares

2006 Rockshox Pike 454 Air U-turn Forks, adjustable travel 110-140mm.
Standard 1 & 1/8" Steerer, length = 192mm.

Given to me by a friend, been ridden a few times, but unknown history before myself. They were working fine for about 20-30 hours riding, and then started to have a recurring problem with losing travel.

Not 100% what's wrong with these; rebuilt 3 times, having the same issue with losing travel. They seem to work fine and feel nice, but during the first ride, gradually ramp up and lose travel. I have explored all the usual options - it's definitely not wrong pressure set up, so I figure there is some kind of leak between the 2 air chambers. This is most likely worn-out internals in the air-spring leg - these could be replaced or you could change the system to coil using a spring such as the one for sale here: http://www.pinkbike.com/buysell/1301456/

Selling as I have no need of these and do not have the time to repair them, require someone with access to a better workshop than my toolbag!

They have a next to new motion control cartridge, acquired from the SRAM stand at Crankworx last Summer.
The stanchions are immaculate and there is only light paint scuffing on the lowers, from hose rub.

Do what you will with them, repair, split up etc. Lowers will work with most argyles/pikes uppers etc.

Pickup from Bristol or Bath.