Park Tool TS-2 Truing Stand Upright Adjustment Knob
RoboKaren was probably right about frozen grease. I decided to install a rebuild kit that is made for this stand. Started taking it apart and got to the step that says to turn shaft to remove it. It still wouldn't turn so I put a long wrench on it and it turned. So perhaps I was being too gentle with it before. At any rate, I'm going to finish the upgrade even though the original parts are probably fine, as this stand was hardly used. Park claims the upgrade will be better anyway. Thank you RoboKaren.