[whiskers]

Inside the microwave above the turntable to the right as you stand in front is a piece of material 4 3/4" long by 4 1/2"wide that has burned a hole in the top causeing sparking inside the unit..What is this piece called and where can I get one....Thank you Whiskers

[woodchuck]

I've heard it called a waveguide filter or microwave filter. When it gets greasy or dirty it can cause the sparking and burning. It needs to be cleaned gently with warm soapy water occasionally. I've seen them on-line for around 8 dollars but the shipping doubles that. I've found the material at an appliance parts store cheaper. They just cut off the size you need.