If the corrosion isn't too excessive, a little WD-40 on a Q-Tip, or even a pink eraser may be enough to remove it. Otherwise, you may need a metal polish, or even some black sandpaper (making sure to keep control of any metal bits). A light metal polish/cleaner like Flitz should keep further corrosion away. (Actually, even something like car wax should work OK at keeping the rust from returning.)
