When your HP LaserJet 4000 is in use, the toner is heated up and fused to the paper to print your text or pictures. During the course of normal operation, the various plastic feeds and rollers inside the printer may become dirty, which occasionally causes vertical lines to appear on your prints. You don’t need to buy a new printer to fix the problem. Getting rid of the vertical lines only requires cleaning the inside of the printer or replacing the toner cartridge. Warnings Writer Bio
