Clean the microwave regularly to prevent impurities from building up on or inside the oven. Use a soft cloth in soapy water to clean both inner and outer sides of the oven. Rinse and dry well. Put a cup of diluted lemon juice on the center of turntable. Heat the oven for 10 minutes at max power. When the cycle is complete, wait until oven cools down. Then, open the door and clean cooking chamber.