I am a consumer of Sears for decades, not a appliance Tech. Most magnetrons are covered by a 10 year warranty. Sears is great in honoring manufacture's warranty of covering the parts and labor. When Sears works on a microwave, they will also test for microwave leakage and safety. In-home service from sears will probably charge a fee if the entire unit is out of warranty, even if the magnetron is within the 10 yr. Yet if you bring the microwave to Sears drop off center, the magnetron will be covered if the unit has the 10 yr magnetron warranty. if you have a receipt, that will be great. If not, the serial number can be used to determine the date of manufacture and confirm with Sears if in warranty.