I've been handed down a 2004 Itasca sunrise 36' gas workhorse and this is the first RV I've had with the HWH 310 leveling and slide outs. So here's the deal, right rear jack doesn't extend needs solenoid, left rear jack extends but won't retract unless I unscrew the check valve at the top of the manifold near LR solenoid (which is very hot) and release the pressure. I don't know if this matters but when I extend the rooms LR jack extends also. And does the pump need to run to retract jacks? Because it isn't.