Comment by ajb

Nice investigation!

My 25 year old microwave is really solid, except for the lamp, which has blown. It's an old bulb so it should be replaceable - except that physically there's no way to do it without unscrewing the magnetron, which is well into scary territory - you need to basically re-qualify it after reassembly by scanning for leaks with a professional instrument. I don't want to throw it away because it still works, but fixing the lamp would cost more than buying a new one.