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Heating the back of your disc can slightly melt the plastic coating and fix minor scratches. You'll get the best results with a desk lamp using a 60 watt bulb. Avoid using heating methods that apply a lot of heat, such as a stove. This will likely melt your disc beyond repair. Stick with a 60 watt bulb. This will ensure that it is giving off enough heat to melt the outer layer. Hold it close enough that you can feel the heat from the bulb. When holding the disc, only grip around the edges and insert a finger through the ring for support. If you hold the disc too long, you may permanently damage the disc. It's better to pull it away too soon and try again than to hold it too long. Take the disc from the lamp and immediately place it in your Xbox. Start up the console and see if your disc works. If it still doesn't work, you may need to have the disc professionally resurfaced.
Find a lamp with a 60 watt bulb. Let the bulb warm up for 5-10 minutes. Hold up the "read" side of the disc 3 inches from the lamp. Hold up to the lamp and rotate back and forth for about 20 seconds. Test out the disc.