If the lever is down, Epson will sense the door is closed. Usually used to detect if a cover is open or closed. Not sure what a part is called? Need the ET-8550 parts list? Want to learn how to work on it? Check out our ET-8550 Exploded Parts Diagram & Repair Reference Guide: https://bchtechnologies.com/products/et-8550-et8550-exploded-parts-diagram-repair-reference-guide-annotated-edition