Get the box in the exact center of its' lock to lock travel. Set the worm gear preload which is the top slotted bolt with the locknut (need more info on that procedure & CW "down" increases the preload). then loosen the big nut on the horizontle sector shaft which is the splined nub on the rear side of the box. I believe on that you grab the coupler/st col shaft & rotate it back & forth slightly and tighten the big nut CW till the play is just zero but confirm on that. EDIT I'll see if I can find my notes on this