Rick

I had a similar problem on my 82 W123 and traced it to the steering box. I could see the slack in the box by gripping the steering shaft above the steering box and rotating it back and forth from where resistance was felt to where resistance was again felt. I noticed that the pitmen arm, the arm connected to the output end of the steering box, moved very little while I moved the shaft. I found that I needed to put a foot long extension on my ratchet to get it up to where I put enough leverage on the lock nut to break it free. Here are two suggestions: 1 turn the allen wrench to where you think it should be, then tighten the lock nut and then test the slack again as the adjusting bolt will turn a bit while you tighten the lock nut. If you find there is still too much play then go through the steps again. 2.0 If you go too far and go beyond just removing the slack, you will not only put undue strain on the internals of the steering box; you will also loose the self centering when you turn a corner. ( the wheel will not turn back to straight.) I hope this helps.

Rick