I've been to a vintage audio site, and the resto guys there use a metal contact deoxidizer called DEOXIT or DeOxIt or Deoxit. I believe Radio Shack carries it. I've never used it, but the posts say that to remove the oxidation from the contact surfaces you spray a very little cleaner on the reostat and wiper then rub them against each other as they would in normal operation for a few dozen or more times.
It seems like it would be better than harsh mechanical removal.


Never start vast projects with half vast ideas.