Why is my Brother laser printer streaking?
This issue is usually resolved by cleaning and/or replacing the drum unit. Brother strongly recommends that customers use only genuine Brother drum units and/or toner cartridges. Each Brother laser printer is designed to work at pre-set temperatures that are matched exactly to each of our individual toner formulations.
Why is my printer leaving black streaks?
When your printer leaves black lines, the lines indicate that there are excess toner powders on the rollers or transfer belt within the printer. As the paper is moved along by the rollers and transfer belt, any excess powder left on them can result in lines being left on the paper.