Canon IMAGE FORMULA DR-7550C Reference Manual page 54

8.
Replace the roller cover.
9.
Push the front of the roller cover in. Check that it
makes a latching sound and that it is securely
returned to its original position.
46
10.
Gently lower the upper unit (a). Press down on both
sides of the upper unit to ensure that it is securely
closed (b).
CAUTION
Make sure that the hook is completely latched and the roller
cover is not loose. If the roller cover is loose, the Document
Feed Tray will catch on it causing the scanner to malfunction.