DIAGNOSIS: Grease and food particles get sucked up into the lid's upper chamber during air frying. They bake on around the heating coil and fan, which isn't submersible.
FIX: Unplug and let the unit cool completely. Wipe the interior of the lid with a damp cloth or sponge. For stuck-on grease, use a soft-bristle brush (like a clean toothbrush) with a little dish soap to gently scrub the heating element and surrounding area. Wipe dry.
IF THAT DIDN'T WORK: For heavy buildup, make a paste of baking soda and water, apply with the brush, let sit for 15 minutes, then scrub and wipe clean. Do not pour water or submerge the lid.
HEADS UP: Never use abrasive pads or oven cleaner on the non-stick interior. Clean the lid regularly—buildup can eventually smoke during preheat and affect performance.