Please check the following points:

• Clean the primary corona wire of the drum unit. To see how to clean the corona wire of the drum unit, click here.
• Make sure the primary corona wire cleaner is at the home position.

• The toner cartridge may be damaged. Put in a new toner cartridge. To see how to replace the toner cartridge, click here.
• The drum unit may be damaged. Put in a new drum unit. To see how to replace the drum unit, click here.
• If you still cannot resolve the issue after taking countermeasures listed above, please call Brother Customer Service. Click here to go to "Contact us" page.