Vertical black stripes on a Brother fax’s received pages are caused by the machine’s corona wire being dirty, or the sender’s scanner being dirty. The corona wire is the electrically charged wire that pulls the toner off the drum onto the paper. It’s a good idea to clean the corona wire at the same time you change the toner. In any case, toners should be replaced after 2,500 pages have been received.
Request your sender to make a photocopy on the sender’s fax machine. If the copy that the sender makes locally is of poor quality, you can bet the problem is with the sender’s machine.
Have a fax sent to you from a fax machine other than the machine in Step 1. If the fax looks good, the problem is with the original sender’s fax machine and not yours. If the vertical black stripes problem exists on this second sender’s fax, clean your corona wire.
Open the front cover and pull out the drum unit and toner cartridge assembly.
Clean the corona wire by sliding the blue tab from side-to-side a few times. Snap the blue tab back into place and re-install the parts removed in Step 3.