I have a kitchen aid microwave that I have replaced. It's fairly clean. It works but it needs a new switch. When you open the door, the microwave turns on. No clue if it's actually radiating and don't want to find out to test it. So it probably needs a new door switch or something. But once you put food inside and actually run it, it heats just fine. The magnetron is under a year old.
If you're handy with fixing things, repair it. In great condition other than the switch.