135 hydraulic linkage

[hd5]

My 135 has quit lifting a heavy load. It will pick the arms all the way up empy, but with a bale of hay it rises very slowly and only about a foot.

If I remove the inspection plate on the right and move the position lever upward the vertical lever will only move the pump lever (the one with the roller) a short distance. If I use my finger I can move the lever toward the rear of the tractor and it raises quickly and smoothly. I am not able to see if it will do that under a load though.
Also if I move the positon lever to constant pumping it does not cause the relief valve to pop, I think it used to.

If I manually move the pump lever the relief valve pops.
It seems I am out of adjustment , I assume the lift cover needs to come off, I have done it before, don't like it.......
What do I need to adjust?
Thanks