Epson Stylus Pro 9900 - Page 185

Pro 7900 and 9900 Field Repair Guide 10/6/10
Sensor (Platen Gap) Removal Printer Component, Software Item, LCD Display, Printer Button Page 185.
5. Carefully remove, and rotate the Sensor Bracket exposing the Platen Gap Sensor.
Expose the Platen Gap Sensor.