Jmor and Soundguy:
I went to farm today and tried the test Jmor suggested.
In Position Control [lever parallel with cover] the lift arms lift to 21" off ground--no higher. This is normally the position of the lever.
In Draft Control [lever pointing down (vertical)] the implement drops to the ground even with Touch Control arm in the UP position. There is no lift at all.
FYI: I had left lift arms in the up position last weekend--all weight of implement remaining on system. It has remained in that position.
Additional info: When I removed the Lift cover to rebuild, I found the control valve linkage screwed out as far as it would go; and it was in a bind, so I turned it in until the binding ended, and no slack was caused. I confirmed that the valve was functional. HOW should I adjust this? and would that affect the failure to lift all the way up? Thank you.