I think someone must have had to repair or replace their level up lift jack cylinder...............are they repairable or do they need to be replaced? The driver side front cylinder is slowly leaking by the internals and dropping the front driver side in storage. It still provides plenty of lift, though.

Find your local hydraulic repair shop or tractor/equipment shop, they should be able to rebuild it for a fraction of the cost of replacement.
If you been stationary for a while I found by extend/retract a couple times would stop the leaking. Be sure to wipe them down with a silicone spray lube regularly before retracting them also prevents this.

I had a small leak on my "16" and it would cover the foot of the jack with oil.. It was coming from inside the shaft and running down the piston..

I did what danny stated above,

I covered the shaft with silicone and wiped it real good making sure I did not miss a spot, I then raised and lowered the jacks several times to make sure the lubricant got over every thing.

This fixed my issue, and it never came back...

They say that you can either have a a small piece of debris stuck between the shaft and the seal, or the Oring could be dried out...