Thank you for using the forums. Have you taken a look at the support pages for your machine? Pleaswe take a look at this solution for Dark Background and see if any of the suggested solutions help. If not then you may need to contact service.
with my 3100 when i replaced last toner the copy is very dark and fax too bright !
i try to select contrast and othe parameters but the copy is too dark ! Also the background is too dark !!
In the past, when photocopied documents very bright, the copy was completely white ! now is the opposit !
i upgare with last fw !
xrox machine has disappointed me from the beginning !