I worked on our built in microwave oven combo, otherwise it was replace both. The magneteon was shot and a new one got sourced from an online appliance parts store.

But if the wave does not match anything then toss it and get a new one. The insides run on "kill you right there" type voltage and require special handling. In addition the diode in there is a bi0tch to test and requires a power supply or the test.
But if you are curious go on Youtube and there is plenty of videos.