steering box adjustment

The allen screw is the adjuster and the 5/8 (I think) nut secures it. (center screw may be allen or not)
Hold the allen and loosen the locknut a couple of turns.
With the steering centered, twist the steering shaft back a forth by hand while turning the allen in (clockwise) until a resistance is felt, then tighten down the locknut while still holding the allen.
If it is loose you should feel the gap closing up while turning the rocking the steering shaft back and forth and turning the center screw in.
You might need to do it again after the steering is turned full left and right.
It takes a little experimenting if you have never done it before, and if you get it too tight you will feel a strange resistance in the steering when crossing over centered.