Oh a fun day...was sitting at a campground with the levelers down..they are the HWH with the springs....the system would not retract the levelers..I opened the T-handles, still no retraction...I ended...
The check valve is probably stuck in the open position allowing flow outward to the pistons but not allowing it to flow back. They are there so if you stop leveling and look at the piston it does'nt retract whilst you are looking at it. Try cranking them down again. May have fixed your own problem. If not, off to the shop or get a repair book.