Canon DR-9080C Service Manual page 315

5
Carefully close the upper scanner.
Do not force the upper scanner down. Doing so might damage the
scanner.
6
Press the upper scanner down firmly on both sides to close it.
If you press the upper scanner down only on one side, the opposite side
will not be fully closed. Make sure that you hear it click into place.
6.2 Clearing Paper Jams
69