I had the repair tech here today, the darn slide came in for him no problem. I spent 3 days trying to get the slide to go in. He shows up and I think my motorhome knew she had to work or else! Nice that it was an easy "fix", greased the drive for the slide (used white lithium grease in a spray can). Ran it in and out several times and it worked every time. So I had the guy look at the jacks. He raised them manually doing the back ones first and then the front. He raised them to max height and then checked the hydraulic fluid level. The tank was near empty. He explained that when the tank gets low that it will suck in air and that will cause the rear jacks to settle back down. Kept it in the up position, added a half quart of transmission fluid and then raised and lowered several times. Works fine now. When I bought the motorhome a bad jack was found and it was "repaired" but they may have forgotten to refill the fluid tank. The repair guy said that when the jacks are auto leveled they do the front first which led to the problem of the rear jacks sucking air.
At least it was a semi inexpensive.