Well, I just adjusted my box today in fact. This is how I done it.
Make absolutely sure the steering /tires are straight -- straight as humanly possible (this is very important). Then there is a nut on top of the box with an allen screw (some are a slot screw) comming out the center of it. Loosen up the nut several turns (not all the way out) while holding the screw in place. Then tighten the scew (let the nut turn), not tight, just til you fell a drag on the end. Tighten up the nut while holding the screw. Check it how it rides. I haven't driven it but the play is gone when I do the following test.
I have one other problem I need to fix before I drive it.
Best way to check if the play is in the box is to have someone rock the steering wheel for you while you look over the whole steering system.