Safety tips for the maintenance of microwave ovens include

Take special care to ensure that no damage occurs to the part of the oven making contact with the door or door seals. Repairs should only be done by a qualified service person. Do not by pass the door interlocks. oven manufacturers generally recommend not placing metal in the oven, particularly not close to the walls, as this could cause electrical arcing and damage the oven walls. Also, because metal reflects microwaves, food wrapped in metal foil will not be cooked, while food not in metal wrap may receive more energy than intended, causing uneven cooking.