Small Scratches
Lighter scratches are the easiest to clear up. With deeper scratches, there is never a guarantee the disc can be fixed. To clean the disc, you can use any cotton T-shirt. These are lint-free and do not scratch the disc. Slightly dampen the cotton shirt and wipe the GameCube disc from the center outward. Do not clean the disc by rotating around the disc or by circulating in a specific area. This removes fingerprints and smudges that emphasize the damage of the scratches. After you have finished cleaning the disc, insert it back into the Nintendo GameCube and see if it runs properly.
CD Cleaner
If the game is still having fits, you may want to use a CD cleaner. This is a device that cleans the disc with a motor. It essentially works as an extremely light sander and sands down the disc to the scratch. This does not cause problems to the disc, as long as you are not continuously cleaning your GameCube disc using this device. After running the disc through the CD cleaner, insert the disc into the video game system and see if it runs properly.
Metal Polish
Dampen a cotton rag and pour some metal polish (such as Bartender's Friend or Brasso) onto it. Rub the CD in a circular motion around the scratch. The polish softens the areas around the scratch, making the GameCube disc easier to read. Polish the CD two or three times, then rinse it off with water. Dry off the disc and place it into your Nintendo GameCube gaming system to see if the scratch repair worked.