All of a sudden, my Phaser 6510 has been printing repeating black (somewhat shadowy) vertical lines on every page. They are a little less than 3/4" apart and fill the whole page. I replaced the toner cartridge; that did nothing.
It could be a problem from black drum cartridge (posiible discharge as per Andy indication), because from your image there is no image interruption on color mode (on lower of the page, cyan/blue text).
Sorry to hear that... that's unfortunate (and surprising).
I personally can't think of anything else to try. But if I do think of something, I will post again.