ok, I just re-read your op...if everything was installed correctly and the top cap was in place, the screw can not "bottom" out, it is impossible without snapping the top cap into...and once the stem is tight you should be able to actually take the top cap off without affecting the steering tube bearings...so if you are tightening the screw all the way and not having any effect on the sterring tube, still have wobble and still able to turn the forks, then the star nut has come up inside the steering tube...you can drive it in with a new star nut set to the proper depth... I use a star nut setter but it could be done with out one, it is just easier with one. At this point I would just take it to the lbs and let them set one for you. If you are never going to do it again no use in buying the tool..