From morning coffee warm-ups to help us power through our day, to late night popcorn popping that makes movie watching more fun, we rely on our microwave ovens like an old friend. Regardless of their size, shape, or color, all microwaves work the same way. A vacuum tube called a magnetron generates the energy that heats your food. A wave guide directs the heat to your food, which is contained in a chamber designed to hold in the microwave radiation. Common microwave repairs involve something in the chamber that's broken or failed, such as a cooking tray or light bulb. On the outside, with heavy use the door handle can become loose or pull off.