A little graphite would probably do it. You could use a soft pencil if you want.. Pencils have a binding agent in the 'lead' to hold the graphite together.. the more binding agent, the harder the pencil... so you want as soft a pencil as you can find and draw all over (or shave some of the led onto) the moving parts.
Just remember it's still somewhat conductive, so you need to be a bit careful with it.