** ET trailer and Lippert both claim the 8K leveling legs and 14K LG legs are not rebuildable... They are in the business to sell new...
A decent local hydraulic shop should be able to rebuild either of the Gen I or Gen II leveling legs and LG legs without issue...
Parts are also available if you know what to look for to get the correct seal parts for them ( mid/rear 8K use same parts ) and 14K Frt LG use different PN parts due to diameter differences between the two ( pistons )
Here are a few PDFs I put together based on info pieced together from various different usrs and posts to aid those wanting to rebuild there Lippert 6 point levelers
If the leak is external and coming from the top cap the usual failure item is either the cap seal oring or the banjo bolt oring on the top cap
** Edited to add : of course if the internal “Hard Parts” are excessively worn then trying to rebuild with new seals may not result in the desired results .. one has to take the unit apart and visually inspect and make the decision based on what is seen
Longevity in the entire six point hydraulic system is :
Wiping the exposed cylinders prior to retracting them
Changing out the ATF or AW32 fluid at least once every 3 to 5 years to reduce the fluid contamination from particles suspended in the fluid