Is it definatly the inner wall, or just the waveguide cover??
If it is the wall, I'm affraid you'll need to buy a new machine because it will only get worse, and you run the risk of it sparking and maybe catching fire. Also, it will pass microwaves around the inside of your unit and it will start to cut out. If it's just the waveguide cover you should be able to get it replaced. I'd check that the magnetron antenna hasn't burnt out first though!
Jon, July 2007
