Clean the outside and the flue outlet

Shell, mouth and flue outlet

The manual (p. 48) and the help centre.

1. Let the oven cool completely.
2. Lift the flue outlet out of its opening to clean it ("Arc's flue can also be removed for cleaning").
3. Spray a non-caustic, bleach-free cleaner on the dirty areas, then clean with warm soapy water and a soft, non-abrasive cloth or sponge.
4. Never spray straight onto the display or the control dial.
5. Wipe it dry with paper towels.
6. Drop the flue outlet back into its opening.