John Deere 3140 priority valve cleaning

The priority valve as its known as for this model of John Deere and other models in other series of tractors controls the priority in which the tractors hydraulic systems are arranged. Since the rear hydraulics are not a necessity for safety then they get isolated from systems like the steering and trailer brakes when they are required. This valve I had suspected was not operating as it should since the rear arms were not lifting unless the steering was jerked slightly.