Do not recommend a red pencil eraser as they are abrasive. It will clean them just fine, but roughs up the surface inviting more corrosion. I suggest starting with alcohol wipes, and don't be shy with rubbing, just don't apply too much pressure - I know, its by feel. You don't want to push so hard you bend something. If that doesn't work, try a white non-abrasive eraser. If that doesn't do it, its try to send it in.
If cleaning the contacts doesn't work, it's probably something else.