Replacement parts for oven-microwave combo units can be sourced from the unit's manufacturer, online retailers such as Appliance Parts Pro, and physical stores such as Radio Shack and Lowe's. The availability of a replacement part varies considerably depending on the unit's brand and which part needs replacing.
Parts for oven-microwave combo units can be broken into two categories: electrical and mechanical. Electrical parts relate to the unit's circuitry and are commonly found through Radio Shack or Mouser. Mechanical parts, such as heating coils, are more difficult to replace. Though Lowe's or other hardware stores often carry replacement mechanical parts, one may have to contact the unit's manufacturer to find an exact replacement.