It's hard to tell from the photo if there is any damage, but you may have some luck by just cleaning the pot strips using isopropyl alcohol and cotton swabs. If there is a way to remove the slider, you should also clean its contacts. If needed, the metal strips (not the carbon) and slider contacts may also be cleaned by gently using a clean pencil eraser, followed by the alcohol and cotton swabs.
I hope this helps.
/Len