Fix it, don't trash it
All together to save the planet 

Mica sheet / waveguide cover for microwave oven

Your microwave oven has a Mica sheet / waveguide cover problem ?

The part is broken and the appliances doesnt work?

A mica plate is present in each microwave oven. Its role is to filter out magnetic waves.
Over time and due to the grease that accumulates on this plate, it can tear.
Sparks when starting up are a sign that this mica plate is damaged and it must be replaced.

* Free shipping for eligible items Do you want to know more?
** Free returns and exhanches : satisfied or your money back for 30 days Do you want to know more?

Here are examples for partial reference for microwave oven :

Where to find the reference?