for once i'm the one with the question. 2013 Allegro Bus 40QBP, HWH hydraulic leveling, four jacks. the rear two come up fine. the front curb side jack stops about an inch short and the jacks-down light on the dash stays lit, so the coach won't let me forget it. if i hit retract again it creeps up a little more and then stops. it's been getting worse over the summer.
i fix slides, not hydraulics. where do i start before i pay somebody 160 an hour to tell me it's low on fluid.
you might be right that it's low on fluid. start there, it's free. check the reservoir level with all jacks fully up, not down, or you'll overfill it. then look at that one jack rod. on an HWH the jacks retract on spring tension, the hydraulics only push them down. so anything that adds drag on the way up shows up as a jack that stops short. a dirty or slightly pitted rod, a weak spring, or a pad full of grit will all do it.
clean the rod with a rag and a little ATF while it's extended, and look at it in good light for rust pits. if the spring is broken you'll see it hanging. if it's none of that, the switch that tells the dash the jack is up can be out of adjustment, but i'd bet on the rod.
ours is a Lippert system on the Aria, a different animal, but the jack that stopped short last year was the one that sat for a month on a gravel site at Custer State Park and got packed with that fine black hills dirt. a hose and a brush fixed it. if anybody here has a Lippert setup, their manuals are up on lippert.com and they're better than the binder that came with my coach.
two things wrong, both cheap. the reservoir was a good half inch below the line with the jacks up, and the front curb rod had a band of crusty brown film right where it sits when the jack is down. cleaned that off with ATF and a scotch-brite pad, very lightly, topped off the fluid, ran it down and up a dozen times. it comes all the way up now and the light goes out.
the spring looked fine. no leak anywhere that i can find, so i don't know where the fluid went over twelve years. i'll check it monthly.
new owner, and a related question now that i have jacks of my own. the campground i'm going to this fall is all asphalt sites. the man at the office told me to bring something to put under the jacks or they'll sink into the pavement in the heat. is that true or is he selling me jack pads?
it's true. hot asphalt in August is soft enough to take a round print from a jack foot, and some parks will charge you for the damage. you don't need anything fancy. a square of 2x12 or the plastic pads from the RV store, one under each jack. take them out of the bay before you push the button so you don't forget, and look in the mirror before you leave so you don't drive off without them. i've donated three sets to campgrounds in Texas that way.