To properly adjust a steering box you have to loosen lock nut on top of box and back out screw to relieve tension. Then loosen the large lock nut where the steering shaft from the steering wheel enters the box. Use a very larger pair of channel locks. Then tighten the inner collar where the steering wheel shaft enters the box. I use a screw driver and hammer to tap that inner collar snug. Be easy you do not want to crack it cause its made of aluminum. Spray WD-40 on it to loosen it up. Retighten large lock nut. Now put steering wheel on center and snug up that top screw and then tighten the lock nut on the top while holding screw still. This procedure is from the Factory Service Manual. You can't just tighten up that top screw and think you are done. That is only half the adjustment of a manual box. That collar/lock nut where the steering wheel shaft goes into the box must be adjust FIRST to get all the slack out of those bearings FIRST then you adjust the slack out of that top screw SECOND. You must have all tension off that top screw before adjusting the bearing preload via the large collar.