Backhoe dipper not functioning

[dunedainranger798]

I have a Long 5n1 backhoe and loader. The dipper cylinder rod does not function when applying the control. In fact, it will actually cause the boom to go up or down.

If I pull back on both sticks then the boom lifts up violently.

I have been working on this machine for almost 6 months now. I rebuilt the backhoe control valve, replaced spool springs, spool seals, seals in between each working section. I removed the pressure reliefs and inspected for broken springs. I also rebuilt the dipper cylinder. When I was attaching the dipper cylinder I applied hydraulic power to extend the rod so I could connect the upper pin. The cylinder actually worked then. It had air in it but it still moved. But as soon as it was fully attached to the dipper arm it doesn't do anything. The engine is getting loaded when moving the control but nothing actuates. Fluid is topped off and all other functions work. This machine doesn't have a strainer or filter (I know completely stupid), so nothing is clogged in that regard.

I am at my wits end with this machine. Anybody have any suggestions what else I can do

 

[GrandpaSmurf825]

If you completely rebuilt the valve stack then you had all hoses disconnected. How did you make sure that no hose could get incorrectly reattached? Two hoses swapped could cause two things to not function properly.