Hi Silvan,
Thank you for using the Xerox forum.
I would suggest that you review the following solutions.
On the Xerox support and drivers page for 7435 search for blurry to see if those solutions may help.
As you can see the resolutions may differ if the original is on glass or printed file.
If that does not resolve your issue you may consider contacting our specific product support experts at the available Fast Track To The Expert link: