they were all broke for minor problems. So don't throw out any microwave oven if there is a problem. Watch youtube first.
If there is no way you could fix. You could take the transformer out, make it a spot welder https://www.youtube.com/watch?v=eVNVNyoHxSM , which is worth at least $100 or even more.
My fixed microwave ovens are:
1. Don't remember the brand, this was the one in the kitchen room where I was still working. A fuse was broken, just bought a fuse from then "Radio Shack". But you have to have a special tool to open the enclosure with a special tool kit. In Harbor Freight Tools, you could find this https://www.harborfreight.com/security-bit-set-33-piece-68459.html :
2. Don't remember the brand, it was my landlord's. A thermal fuse was bad.
3. Sharp brand. The LCD display connection was bad.
Check item 7 in https://blog.wenxuecity.com/myblog/40376/202304/11239.html
4. This one. GE brand.