It is not "rocket science". The magnetron was bad. I found a document showing how to test a magnetron and I found schemetics (none of which came from replies to this post). I observed all the safety rules and replace the magnetron myself with no problems. Everything works like it should. The part was about $55 (including shipping) which is better than a new $500 microwave.

I found a site that gave troubleshooting steps for the magnetron. I set the microwave on a workbench and removed the cover. I located the magnetron. It has two main wires going to it. For safety, I had a wire connected to chassis ground and a screwdriver. With the grounded screwdriver, I touched everything I planed to physically touch to discharge any voltage. I then removed the 2 connectors from the magnetron. I got my ohmmeter and set it to the lowest resistance scale. I measured from one magnetron terminal to the other magnetron terminal in both directions. The resistance reading was less than one ohm, which is OK. I then set the resistance scale to the highest setting and measured between either terminal to the magnetron frame. Mine read 570 ohms, but the reading should have been infinity (or open circuit). There it is. My magnetron had shorted to its frame. I replaced the magnetron, reinstalled the cover, and reinstalled the microwave over our stove. It works like a champ. If you have internet, search "How to test a microwave magnetron".
The big thing about doing any work on the microwave is the safety issue. Always ground or discharge anything (maybe several times) before you touch it. There is potential to be shocked very badly.