We have a lift here in the shop, the customer stated it would not travel in all directions sometimes. I have been able to repeat this in the shop by depressing the inching pedal during directional change side to side or forward. I notice when the event occurs the 4 port valve connecting the drive wheels does not sound like the fluid is flowing thru it. If i tap on the valve or rotate the coil it will start hissing as the fluid begins to flow and then it will travel ok. It takes several attempts to repeat this event, am I looking in the correct area to repair?