[Alan Douglas]

Unless you have good close eyesight (or a binocular microscope), and steady hands, you're better off just living with it. If you do try, find a clean area (meter magnets can attract particles from interstellar distances) and use slivers of masking tape on toothpicks in the gap to remove the bits of corrosion. Absolutely no compressed air, no magnetic tools, and don't touch the hairsprings.