The only reason to adjust the steering box is IF you have excessive play (left to right) in the steering wheel. The only regular maintenance to be done to the steering box is checking it has plenty of lubricant assuming it is a manual steering box and not power steering. Most owners (manual steering) replace the gear oil with corn head grease (also known as grease 0), it is less likely to leak past oil seals.
For your added information, if you notice the steering wheel moving up and down as you steer the tractor that is an indication of bearing failure. Usually from a lack of lubrication and will require rebuilding the steering gear.
Here is the adjustment procedure from the Ford shop manual.
Adjust the sector shaft as follows:
a. Loosen the left sector shaft adjusting screw, then turn the screw several turns counter-clockwise.
b. Loosen the right adjusting screw lock nut. Turn the adjusting screw clockwise until there is no perceptible end play in the sector shaft. Tighten the lock nut securely without disturbing the end play.
c. Turn the left sector shaft adjusting screw clockwise until there is no perceptible end play in the left sector shaft. Tighten the lock nut securely without disturbing the end play.
d. Turn the steering wheel full left and full right and determine the center point where the steering gear is in the straight-ahead position. At this position, the Pitman arms should have no perceptible free play. Readjust if necessary. Total pull at rim of steering wheel with gear over center, must he 2 to 2.5 lbs. when properly adjusted.
