4020 3-point not working

1. It was not working when I bought the tractor and do not know the history of how it quit working.
2. I do not know if it quit working all at once or if it slowly started acting up.
3. The draft link arms are currently off the tractor.
4. The rock shaft arm moves freely my hand
5. The lever on the counsel is connected to, and moves the cable back to the rockahaft valve assembly.
6. All the other hydraulics on the tractor are working fine
7. I have adjusted the speed adjusting/throttle valve both faster and slower with no results
8. I have good oil flow to the inlet to the rockshaft valve assembly
9. I have tried Load, Depth, and Load-Depth control with no difference

I have a copy of the service manual for this tractor, SM-2039 (7-63). I have reviewed section 270 but do not see any information on where to do pressure checks??

My next step is to remove the rockshaft valve assembly from the rockshaft housing to see if there are any internal mechanical levers or linkages that are broken.

Does anyone have any other suggestions or previous experience with such a problem.

Thanks

Is the wishbone under the tractor free to move?Its possible for the front bushing to have worn a spot in it that won't allow the wishbone to move.Jack it up a bit to where it can be sure to be able to move.Then try to adjust the system.

If the valve operating lever has been removed at some time in the past, the timing could be out of wack.Its very easy to do.Take the cable off the lever and turn the lever as far as you can with the tractor running.Does this cause the rockshaft to move?If so,the timing is off.

If the rockshaft has ever been removed then the cam follower could have fallen forward and it no longer against the cam.See #13 page 270-5-12.Can't remember if the cam follower can be seen through the bung hole,but you might look with a flashlight.

The valves rarely ever get far enough out of adjustment to affect the operation of the system.They are very tricky to adjust too.Good luck.