~~The underside of your scanner cover or the scanner glass may be dirty, or scratched. Make sure they are both clean and that nothing is on the scanner glass. Then close the cover and retry this test. You may also cover the scanner glass completely with a white sheet of paper and retry this portion of the test.
~~If you are using an Automatic Document Feeder or Transparency Adapter, you must replace it with the original scanner cover, since its underside will have different light response characteristics.
~~If the underside of your scanner cover is badly marked, or if your scanner glass is badly scratched, it may need to be replaced. Contact your dealer or refer to your scanner documentation for Hewlett-Packard warranty and service information.
