If NONE of the jacks retracted with the T handles opened and they did when you cracked the lines---Your SHUTTLE valve is bad. You need to replace it. The Shuttle valve is the valve on top the manifold that has a small 1/4 inch U shaped metal line. Page 11 will show the location of the shuttle valve. There are NO check valves on a HWH system that will cause retraction problems. Also, the Solenoids with the T handles are what STOP the jacks in place when you stop the pump, not those check valves. IF there is a part installed at the Hyd line at the manifold it is a VELOCITY(not all HWH systems Have these) valve, not a check valve and its purpose is to slow the return pressure of the jack fluid when retracting, to keep the RV from dropping too fast. The SHUTTLE valve is the gateway for ALL fluid from the pump on extend and back on retraction. When it sticks NO fluid will flow back to the pump. Usually a sticking Velocity valve will operate on the pressure side, because the 3000 psi of the pump will overcome the sticking valve, but the static pressure when you retract cannot overcome the stuck valve. Also, odds are if you operate the system again the jacks will extend and retract. Once you crack the lines and remove the static pressure on the SHUTTLE valve, it sometimes unsticks. REPLACE regardless as it WILL stick again. Doug
http://www.hwhcorp.com/ml33832.pdf
