HP 2820 - Manual (Page 211)

Changing the automatic document feeder (ADF)
If the ADF is damaged or not working, you can replace it. For information about ordering
supplies, see
Accessories and ordering information .
To change the ADF
1. At the device, open the ADF cover.
2. Disconnect the connector by squeezing the tabs together and lifting upward.
3. Remove the ADF by lifting it upward and tilting it forward as the hinges nearly disconnect
from the device.
4. On the new ADF, unfold the hinges.
ENWW Changing the automatic document feeder (ADF) 195