There are people on this forum that have rebuilt or had someone rebuild the "non-rebuildable" jacks. The same ones you and I have.
From my notes here is one thread >>> https://www.irv2.com/forums/f101/lev...nt-384810.html
Here is some more info posted by car54don:
The company in Kentucky that was involved with manufacturing original Kwikee, now does rebuilds.
Custom Cylinders International Inc.
1220 Enterprise Dr.
Winchester, KY 40391
P.O. BOX 4242
Winchester, KY 40392
At a minimum, I would try another shop.