When copy or printing, a dark streak in center of copy

Check and clean mirrors.
also check toner.
its can be bad drum cleaning or developer.

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

IF YOU ARE ONLY GETTING THE LINES WHEN YOU PUT THE DOCUMENTS INTO THE TOP FEEDER AND NOT FROM PRINTNG TO COPIER OR IF YOU PUT A COPY ON THE GLASS UNDER THE DOC FEEDER AND NO LINES APEAR CHECK THE SMALL GLASS WINDOW UNDER THE DOC FEEDER THERE MAY BE SOME TIPEX OR INK RUBBED OFF AND LEFT ON THE GLASS THERE.. THISD MIGHT BE CAUSING THE STREAKS YOU CAN CHECK THIS BY PUTTING THE PAGE IN THE DOC FEEDER AND DOING A COPY AND THEN PUT IT ON THE GLASS PLATE UNDER THE LID AND DO A COPY OR IF HOOKED UP TO COMPUTER DO A PRINT JOB.. IN NO STEAK APPEARS YOU CAN BE SURE ITS ON THE THIN SCANNER GLASS.. GOOD LUCK ...a

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.

I don't know what model you're using, which would be very helpful, however, if you lift the Document feeder section where the originals are fed, there should be a narrow piece of glass, which is only used when the Document feeder is used. This must be completely clean -1 spec creates a solid line.

yes directly

Dark streaks are an indication of "burned" or overheated ink. This will occur when the printer sets for a long period of time and nothing is printed. The problem will usually disappear after 50 pages or so, unless the printhead is damaged.

If the print remains dark, the printhead will need replaced.
(Very expensive)

(Dark print can also be caused by using Non-Xerox ink)

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

hi im jules_09.have check the drum unit and the fuser unit check the two unit.first of all the drum unit the drum may be scratch or damage that goes with the fuser unit too.

can only be toner, drum or fuser, pull out drum and look at surface are you streaks present? usually drum.

Stop a print half way threw machine and then remove drum and look at print, pre hot bit (fuser) are you marks there? If so it is drum, if not fuser.