Copies come out with dark/grey streaks on both edges and a lot of black dust inside the front cover

1st the basic cause of dark/grey copies DUST. Clean w/ alcohol cloth then dry cloth totally all mirrors and the platen glass both side. If still dark check the "Optic slit " right in the upper of your halogen lamp remove it, still dark Check your halogen lamp maybe it already oxidized. The last solution adjust the CVR .

Here is a great how to on Black Streaks issues with any printer.

http://www.ehow.com/how_5966540_troubleshoot-black-lines-copies.html

Try doing a "stop test." You would induce a jam before the paper reaches the fuser.

Just open a cover while printing and hopefully some image has been transferred to the paper. If the defect exists already then the laser unit, or document scanner may be causing it.

If that eliminates the dark streak, then obviously the fuser FG6-3720-000 should be changed.

Whit
Item, Inc

need to replace the door ring, " boot ".  new ones made of better materials and chance of any odor greatly decreased..

If this is only happening with copies and not straight prints, it is possible that the problem is with the scanning unit. Use the soft cloth to clean the scanner area to the left side of the machine where pages are scanned when run through the page feeder. A spec of dust or other debris in this area will appear as a streak along the length of the page.

If it occurs on all prints, You may need to replace the drum or clean the fuser unit.

check the drum

Did you clean the lens and the mirror under the lens cover? If so, There is a VR behind the front cover of most small Xerox machines. One VR makes the image darker/lighter and one VR changes the lead edge registration.

the document feeder of that unit have its own scanner glass. try opening the document feeder and clean the scanner glass with a lint free cloth that is moist with water and also clean the rollers of the document feeder

Good, so u are having probs in ADF. Open the cover, lift the rollers and u can see the scanning glass. Take a lint free cloth and clean it. it will be ok.

bit vague...Cq not good? What does that mean?
Light copies> could be related to toner or ROS unit (laser unit)
if prints OK but copies U/S clean mirrors and ccd lens
Dark copies , streaking? Cleaning blade /drum unit U/S
or could be streaking from fuser roll
Patchy copies , dark edges, light edges ???????
more detail please