M936A1 Boom not lowering

[Cylde]

Looking for some input on 1986 M936A1 wrecker, not booming down.

 

[Cylde]

Anyone know how the oil routes thru crane control valve allowing boom elevating cylinders to retract?

 

[simp5782]

Bad flow valve on the control handle. It should come back down on its own even with gravity with the valve open. The return flow hose may also be restricted

Drop the cable down and secure it to the truck then cable to get a little pressure on it then pull the boom Down lever