JD--I followed the manual link and downloaded the '93 manual. It has instructions for adjustment, and they are similar to what Mike mentioned. But let me ask another question: if the gear is either over- or under-tightened, then that would prevent return to center? Maybe what I had was looseness preventing it in the beginning, and then an over tighten preventing it now? If no, how does one get it back?
There was only play in the beginning, which was due to the steering box, and hence removed by tightening the screw atop the box. No more play now either side to side, nor by pushing/pulling on the wheel top and bottom to check ball joints, nor the push/pull from side to side on the wheel. And a shop confirmed the last time I was in that the gear box needed to be replaced (adjusted?). So, I'm willing to give anything a try...but I'll probably have a new gear box on standby in case thing go awry. :-)