how do i clean the inside roof of this microwave? it's got splatter baked on and the manual says not to scratch it.

Diagnosis

The "roof" of the GE JES1097SMSS is not a solid metal surface; it features a critical component called the waveguide cover (often referred to as the mica sheet). This is a small, rectangular piece of pressed mica or cardboard-like material located on the upper right-hand side of the interior cavity. Its purpose is to allow microwave energy to enter the cooking chamber from the magnetron while preventing food particles and grease from entering the internal electronics. When food splatters onto this cover, it doesn't just sit on the surface; it bonds to the porous texture of the mica. Over time, as you continue to use the microwave, these food particles are subjected to intense microwave energy, causing them to "carbonize" or bake on. If these carbonized spots are not removed, they can create a focal point for electrical arcing. This is why you may see small sparks or a "crackling" sound during operation—the microwave is essentially trying to heat the burnt food particles on the cover rather than your meal.

How to Fix It

To clean the waveguide cover without scratching or puncturing the delicate material, you must use a steam-softening method. Avoid all abrasive pads, steel wool, or harsh chemicals like bleach, which can degrade the mica.

1. Fill a microwave-safe glass bowl (approximately 2 quarts) with 2 cups of distilled water and 2 tablespoons of white distilled vinegar or fresh lemon juice. The acidity helps break down the molecular bond of the baked-on grease.
2. Place the bowl in the center of the microwave. Ensure the bowl is not touching the side walls.
3. Set the microwave to High power and run it for 5 to 8 minutes. You are looking for the window and the interior roof to be completely fogged with steam.
4. Once the timer expires, do not open the door immediately. Let the microwave sit undisturbed for 10 to 15 minutes. This allows the steam to penetrate the hardened carbon layers on the mica cover.
5. Open the door and carefully remove the bowl. Using a clean, microfiber cloth or a soft sponge, gently wipe the mica cover. Use a "dab and swipe" motion rather than scrubbing.
6. For stubborn, petrified spots, dampen a paper towel with a mixture of mild dish soap and warm water. Press it against the spot on the roof for 60 seconds to re-hydrate the debris, then gently wipe away.
7. Wipe the entire interior cavity with a dry cloth to remove residual moisture before the next use.

If That Didn't Work

• The Paste Method: Create a thick paste using baking soda and a small amount of water. Apply a thin layer of the paste only to the stained areas of the mica cover. Let it sit for 30 minutes, then gently wipe it away with a damp sponge. The baking soda provides a very mild abrasive action that is safer than a scrub brush.
• Replacement of the Waveguide Cover: If you see any black char marks, pin-sized holes, or actual burns on the mica sheet, cleaning will not fix it. The material is permanently damaged and will continue to arc. You must replace the cover (Part Number: WR13X10542 or similar depending on the specific production run). This is a simple snap-in part that does not require tools to replace.
• Deep Degreasing: If the splatter is oil-based and resists steam, use a small amount of rubbing alcohol on a cotton swab. Gently dab the specific spot of grease and wipe immediately. Do not spray alcohol directly into the microwave cavity as it is flammable.

Heads Up

• Never Use Metal: Never use a knife, screwdriver, or metal scraper to remove burnt food from the roof. A single puncture in the mica cover can lead to the magnetron overheating or causing a fire.
• Avoid Harsh Chemicals: Avoid using oven cleaners or caustic degreasers on the waveguide cover; these chemicals can eat through the mica, compromising the seal of the waveguide.
• Preventative Maintenance: To prevent future buildup, use a microwave-safe cover or splatter guard over your food, especially when heating sauces or oils.
• Check for Arcing: If you see sparks appearing on the roof even after cleaning, stop using the unit immediately and replace the mica cover to avoid permanent damage to the magnetron.