If have detent on valve spool that could have come apart preventing spool travel in one direction check this by measuring spool travel should be same both directions. If travel is ok port relief could have stick open most time this cause by packing material in valve are inner tube of hose came apart got to port relief. Most all valves have main relief and port relief and check valve this is big slotted screw for giant screwdriver or allen wrench socket. Again if travel on valve spool to little one direction it be center spring holder on opposit end from where lever hooks to spool they be either 2 bolt are 4 in cap take that off to check that bolt are spring not broke are lose. You can reverse hose on valve to cylinder port if problem changes direction it be in valve if don't it be in cylinder. One direction is ok so that lets pump out of being problem. If find dabre in valve it come from piston packing most likely and need new kit put an ear up to cylinder you hear oil russing by piston after bottom out stroke.

Thanks. Will check the valve today to get a better idea of the problem. Like the idea of reversing the hoses to isolte the problem too.