Remove the cover above the spare tire well in the trunk. Underneath, you'll find a locknut for the roller shaft adjusting screw. Loosen the lock nut and turn the screw slowly clockwise until you feel the roller contact the worm (if it does). We tightened this down as far as it would possibly go with no positive results. Play must not exceed 15mm, but if yours does (and ours did by a long shot), you should replace the box. But we'll do that later.