Old style headsets with two big nuts on top are really easy to permanently damage when adjusting; The person snugs down the bottom nut, even just hand tight, but that nut is pushed up against the "top" side of the threads; Now they tighten the top nut (often with a 32mm wrench with a huge handle because the other end is a 15mm pedal wrench, so too much leverage), pushing the bottom nut down across that thread gap, and it is just enough to push the bearing balls into the cups and dent ("Brinell") them, if the bearing races are stamped and not that thick. Look for brinelling. When readjusting, always start from too loose, tighten nuts, if needs more, a little more, etc. You can't overshoot or the bearing cups are damaged. I think newer better quality headset cups may be more resistant to this. Also much easier to avoid with newer "Aheadset" style adjustment.
Last edited by Duragrouch; 02-26-24 at 05:07 AM.