DIAGNOSIS Grease and food particles splatter upwards and bake onto the heating element and the interior roof. It's normal, but needs careful cleaning.
FIX Let the unit cool completely. Remove the basket and pan. Fill the basket with hot water and a few drops of dish soap. Place it back in the fryer. Run the unit at 350°F for 3 minutes. The steam will soften the gunk. Unplug, let it cool again, and use a soft, damp sponge or non-abrasive brush to wipe the interior roof and element. Don't scrub hard.
IF THAT DIDN'T WORK For stubborn, baked-on grease, use a paste of baking soda and water. Apply it gently to the spots, let it sit for 15 minutes, then wipe with a damp cloth.
HEADS UP Never use metal scouring pads or abrasive cleaners on the interior. You'll scratch the non-stick coating and the element itself. And never, ever submerge the main unit in water.