I had the same problem, and based on suggestions from this forum, cleaned the area around the jacks where the cylinder goes up into the housing with some WD40 and some Q-tips. They now go up fast.
Seems all the road debris causes too much friction and the jacks don't retract.
Tom and Katharine
'07 Winnebago Tour 40TD, 400hp Cummins
RVing for 19 years & 150,000+ miles