It will depend on what is worn/bad. There are two basic adjustments on a manual box. The worm gear end play adjustment is what puts a slight preload on it's bearings. If there is slop in there, Stop. Most likely you have a bad bearing and probably a bad surface on the worm gear shaft. That will require pulling the box and rebuilding it. If that adjustment is good (made by loosening that huge threaded lock ring and turning the aluminum end cap), then the next adjustment is the one between the worm gear and the sector roller. That has to be done with the worm gear centered and no load on the steering linkage. Pulling the center link loose from the pitman arm is good enough. Once centered, loosen the lock nut on the adjuster while holding the adjuster from turning with a screw driver. It's now more of a matter of feel on the adjustment. The adjustment screw should move freely. Rotate the adjustment screw back and forth 1/4 to 1/2 a turn to get a feel for it. Turn the adjustment screw clockwise GENTLY to just take up any free play. Do not overtighten! Once you feel that the adjuster has taken up any slack, hold the adjuster and tighten the lock nut. If the top end of the adjustment screw is even or below the top edge of the lock nut, that indicates that there is a lot of internal wear. Slowly turn the input shaft back and forth to see how it feels. It should move smoothly and have no binding or hard spots. If it does, you probably will need to get the box rebuilt. It's not hard to do, but, you need to find a supplier of the internal parts. Bearings and seals are readily available, but, some of the other hard parts are a bit harder to find and much more expensive. You should get a factory manual to do a rebuild as preload, adjustments, and the actual procedure needs to be followed carefully if you haven't done one before.
