I have an over the range kenmore that is right around 5 yrs old. It runs like normal and sounds normal but will not heat anything. I read online it could be a diode, door switch or magnetron. I also called a local appliance repair shop and he basically said he don't need to come out, he knows its the magnetron cuz its a kenmore made by samsung and its made cheap. It was probably $3-400 brand new so i don't want to replace if i don't have to. Any thoughts?

I was also looking at getting some sort of warranty protection that covers appliances but I'm not sure it would cover this? And if it did, would they be able to tell it has been broke for some time? Not sure they would cover it if they could tell it was broke before the warranty began.

Any help would be greatly appreciated.