If the hole is in the wave guide cover, that can be replaced. After removing it, you would need to inspect the inside of the wave guide, and clean it if there is food or grease in it. If any arcing has occurred, damaging the paint, it needs to be repainted.
If the hole is in the metal part of the cavity itself, that can be dangerous, and it's generally impractical to repair.
If you need further help, I’m available over the phone at https://www.6ya.com/expert/david_29ad5d1dd86564b0
Answers & Comments
If the hole is in the wave guide cover, that can be replaced. After removing it, you would need to inspect the inside of the wave guide, and clean it if there is food or grease in it. If any arcing has occurred, damaging the paint, it needs to be repainted.
If the hole is in the metal part of the cavity itself, that can be dangerous, and it's generally impractical to repair.
If you need further help, I’m available over the phone at https://www.6ya.com/expert/david_29ad5d1dd86564b0