Problems I have deep black vertical lines on my scanned in documents. All parts have been cleaned!

I just called the Xerox customer support number (800-648-0410) and they solved that verticle line problem in 10 seconds. Here's the solution: Clean the white-strip raised section on the top portion of the glass with some isopropyl alcohol on a rag. There is a piece of dirt there that shows up as a line when it runs through the document feeder. If you're just scanning on the glass, you don't see it because it's just a spec of dirt, but through the feeder, the dirt shows up as a solid line throughout the whole document. By cleaning that section off, it takes out the line. Viola! I worked for me. That's the second time I've called Xerox for a problem with my scanner, and I would like to report that their customer support is awesome!

If the the scanner is based on lLED then probably one of the LED is not working, and if this is florescent tube based then there is somthing wron with the CCD or the Reflector. open it and check it for a spot in the reflector.

Assuming the the Glass is cleaned-  and the device is mechanically functional- then the only other thing to go wrong is the CCD- the image capture device- at that stage I suggest there is no repair feasible only replacement of the whole unit.
However a trawl of the Visioneer Web site/customer support may  give a clue.