My son told me that almost all the microwave ovens that came into the repair center he worked at, 15 years ago, had a defective magnetron. I ordered a magnetron, and sat back until one shipped. The one that came, the first time, was in a small factory cardboard box, which was in a large bubble-pak Fedex envelope; which didn't show any signs of abuse. Inside, however, the factory box was beat up. Removing the magnetron, I noticed that the socket, as well as its' pins, was bent, and loose in the steel case of the magnetron. I straightened the socket and pins as well as I could; but the socket was still loose in the case. Looking the magnetron over, as I considered rejecting it, out of hand; I noticed that the waveguide nose was fairly badly dinged. I heard, years ago, in the Army, that waveguide had to be perfect. I called customer service, and got a representative named Dixie. I told her my problem, and she ordered another magnetron, The second one was packed in a cardboard box, with the factory box, inside. No signs of damage. The magnetron looked pristine, so I began exchanging it. I took my time, and was done in less than 2 hours. I used a #2 phillips screwdriver to remove the trim and key face. I used a stubby #2 phillips screwdriver to remove three screws holding the magnetron cooling fan in the cabinet. This gave me much better approach to the four screws holding the magnetron in place. To remove and reinstall the 4 screws holding the magnetron in place, I used a 1/4" drive screwdriver handle, with a 1/4" hex socket, with a #2 phillips bit in the socket. This was the correct length, to get at the hardest part of the job. I used a mini channel locks, to turn this tool, for initial loosening, and final tightening of the four magnetron screws. I recommend taking pictures of everything critical; like the three leads on the fan, and the overheat sensor on the magnetron. Make sure the oven is unplugged, while working on it. My 4,000 volt capacitor has a drain resistor built in; yours may not. Success. I wouldn't have tried to repair this oven, if it wasn't such a job to take it down from the cabinet, and put a new one up. My wife bought a $53 microwave, to tide us over, in the interim. Many thanks to you, Dixie. I don't believe there will ever be another repair, like this, for me. I believe the first replacement magnetron was damaged somewhere between China and the warehouse in Louisville, KY. The challenge of this job, was making 75 year old fingers work in the cramped quarters.