[rdunk]

I have previously had extend/retract problems with my front jacks, but for me, it has never been due to a bad ram - ie. up-graded pump needed, air in lines, low fluid in tank.

I've had a small leak in a rear jack for several months, while stationary. Last week, I had a mobile service tech check for the cause of the leak, and found the problem to be due to one fitting being cracked, and another fitting was scoured, (best report for a potential bad problem). He replaced the fittings, thanks to Lippert for a supply of fittings I had left over from a prior problem.

Because some hyd fluid had leaked out, I did add what I thought was enough. I cycled the rear jacks several times, and they worked fine. However, I could not get the front jacks to lift for hitch-up. I added more fluid, and fairly quickly, they began to lift normally.

I did have a bad rear jack once that had to be replaced, but is was clearly leaking.

You don't mention seeing a leak, so your hyd tank may have "plenty" as you say, but based on my experience with my hyd tank, one can fill it to 80% or more without a problem. Might be worth a try to add a little just to see if that might be it. (Mine requires DexronIII - 2005).

Good luck.