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. Wipe the windows of all four LED heads with a dry lint free soft cloth. Click here to see the details of how to clean the LED head.
   
   
3. The drum unit may have the dust or glue on the drum surface. Clean all four drum units. Click here to see the details of how to clean the drum unit.
   
   
4. The toner cartridge may be damaged. Put in a new toner cartridge as follow:
   
   
   1. Click here to print the chart. [185KB/ PDF]
   2. Compare your printed document with the printed chart to identify the missing color.
   3. Replace the toner cartridge of the color. Click here to see the details of how to replace the toner cartridge.