A cooking appliance such as a microwave oven is provided with a sacrificial region for repairing damage caused by arcing and related failure modes. The sacrificial region incorporates a component that, when damaged, is removable from the cooking appliance for replacement by another component of similar construction. In one implementation, a sacrificial component is utilized in a microwave oven with a heated cavity subject to microwave radiation from a magnetron. The sacrificial component in this example includes an aperture that communicates with an opening in the cavity, and through which the radiation impinges into the heated cavity.