Remove the document cover, you will find two screws in the hinge pockets.

You have to remove the front cover (bezel) to get to the hidden screws. Click on the thumbnail to read the instructions on the image.

Front cover removed.
Click on the thumbnail to read the instructions on the image.

Top View showing the location of the screws.

Quote from Chris: "Once the cover was loose I simply unplugged the small ribbon cable that attaches to the front controls. I used the cleaning procedure as described on your web-site [Canon8400F] (thanks again for this). I did not dig any deeper than cleaning the haze off the platen as I was not sure where any mirrors were located. I might tackle that aspect in the future if needed. Perhaps I should not have, but dishwashing soap (Dawn) did not remove the haze very well so I did end up using blue Windex. I can't discern any adverse effects on the window. There is still a trace of haze left, but it is much better than it was. Re-assembly was simply the reverse of the above."

I recommend using Isopropyl Alcohol for cleaning the glass instead of Windex. Webmaster