I am no expert, so,,, If you have made sure all your suspension and steering linkage has no slack in it, I have tightened the steering box a little on GM cars. If you overtighten it you will probably have a hard spot in the center position which I think is to tight. Your car is close to 30 years old with many hours on the steering box. You can try to loosen your box a little and may be satisfied. If not, new box time. Make sure you get the correct box as there are several to pick from. Hope this helps and is clearer than mud.