Black vertical lines printing

Do an interrupted print, print a job and open the top cover when the paper starts to feed out. Remove the paper and open the cover on the toner cartridge to see the remaining print image, check to see if there are lines that match up with the paper. If the toner cartridge is clean, check the fuser for toner stripes. You can also try to match the vertical lines with the exit rollers, if they match you can see which rollers to clean. Repeating image defects usually show up 3 to 4 times horizontally on the page, this can be the toner cartridge or the fuser.