Over the course of my tenure in the residential cleaning business, I have found (3) ideal steps to cleaning a less than stellar microwave. I.e. excessive amounts of spaghetti on the top and hardened on cheese and other substances stuck to the glass tray. Tip #1 Always first spray the entire inside of the microwave with a cleaner. #2 Place a coffee cup filled with water in the microwave and turn it on for at least 3, but preferably 4 minutes. Once you have done this you can use either a form of Scotch Brite pad or a damp cloth to literally wipe any debris that was once previously hardened on before. Note: If the interior is stainless steel, do not use a Scotch Brite pad for you could possibly scratch the stainless. Instead place the coffee cup back in for another cycle of 3-4 minutes. Finally #3 you can carefully use a razor blade on the removable glass tray to clean any heavily stuck on debris or residue that a cleaning cloth could not initially remove. Hope these tips help. I’ll be back in a couple of weeks with some more helpful tips to make your life easier.