6/23/2015 5:06 AM
The portion of the lift valve, solenoid, may not be holding, you can try switching them around and see if they stay. However the fact that it's the rear two with the center may have a bad o-ring or something in the steering, those three lift units are tied into the steering circuit. I know you said you tried changing the cylinders, but I cannot remember on those as it's been so long since I've worked on one if they all drop if one is bad or if it's the outer two and the middle three depending on the one that is leaking internally. I'd cap both lines go to one rear cylinder and try, then hook back up and move to the next, and then to the center just to be sure. if you've done it like this already then your going to need to look at relief pressures, and cartridges in the lift lower valve, and possibly the steering. I know I had this issue many years ago but I cannot remember what it was. If I do I will be sure to reply back.
Regards,