Please check the following points to solve the problem:

1. The drum unit or toner cartridges may not be installed correctly. Re-install the drum unit and toner cartridges.
   
   
   • Click here to see the details of how to install the drum unit.
   • Click here to see the details of how to install the toner cartridges.
     
     
2. The drum unit may be damaged. Put in a new drum unit. Click here to see the details of how to replace the drum unit.