Please check the following points to solve the problem:

1. Check the machine's environment. Conditions such as high humidity can cause white spots or hollow print.
   
   
2. Make sure that the media type settings in the printer driver and in the machine's Paper Type menu match the type of paper you are using.
   
   
3. 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.
     
     
4. Clean the drum unit. Click here to see the details of how to clean the drum unit.