I just rebuilt mine a couple of weeks ago. That screw, (it's actually a bolt), coming through the plate (and that plate is threaded)......looking at it, keep turning it clockwise (as in tightening mode), and it will back out all the way through the plate. If you're saying you are doing just that, and it is stopping half way, then there has to be a burr on the threads catching when it gets to that point. Mine screwed all the way through, no problem, and the cover plate separated from the shaft. That bolt, with a shim on it, sits in a slot on the end of that shaft, that you cannot see until you get the shaft and plate apart.
These steering boxes are very simple. I was a little unsure about doing mine. But if it ain't working anyway, might as well take it apart and find out why. Upper and lower bearings on mine were a little suspect, so I replaced them. That's all I replaced, other than gaskets I cut myself.
Follow the rebuild and adjustment instructions exactly as the shop manual says. My truck steers 100% better now. I would say the CORRECT adjustments, as per the shop manual, is what made the most difference.
Last edited by kades51; 12/17/2019 8:29 PM.