Is it safe to use aluminum foil to cover the crumb tray or inside the oven?

Do not cover the Crumb Tray or any part of the oven with metal foil, as this will cause overheating. If you choose to use foil to cover the Baking Pan/Drip Tray, make sure the foil is cut to neatly fit inside the pan and does not touch the walls or heating elements. When using aluminum foil as a cover for accessories, it prevents fat from dripping into the Drip Tray and grease can accumulate and may catch fire. (Pages 3, 5)