As often said on this sub, maintenance is another key to keep your stuff for decades, if not for life.
Microwaves have a consumable part. It's called the mica plate. It's the cardboard-looking square you can find in your oven. When it's dead, sparks are ejected in the oven, and you might think it's broken.
In fact, the part comes in packages of 5 or 10 for under $10 on any website, and you can change it with just scissors. #lifestyle