QUOTE(neil30076 @ Oct 20 2009, 09:35 PM)
You can clean them with a very light ( 600 grade) emory paper, but once the face is worn off it won't last long.
Buy a new set - good for the next 6k miles at least!
I was always under the understanding that sanding (enory parer including) contacts was bad. Maybe a file but not sanding.