Canon 9000f MK2 black line top right edge

[9000fblack]

Scanning of top left of glass area produces a gradient looking black line as seen in the top right of the following image:

http://s31.postimg.org/4n4hv5vaz/blackline.jpg

Also, a rounded corner of the document cover is seen at top left of the image.

They are more easily noticable if one saves an image then opens it.

If one covers those areas on glass with a document black spots are not seen on the produced image.

White document cover attatched to the inside of a lid appears to be in an OK position.

What's wrong?

Does your scanner produce spot free images when glass edges are not covered with a document?

Thanks.

[9000fblack]

Ok after some testing I found out that white document cover is not aligned properly with the black plastic that it's glued to so black horizontal line appears at the top edge of my scans. I've heard that the black plastic that holds the white document cover is discontinued and can not be replaced/bought anymore. Is that true? Can the document cover at least be realigned?