Please check the following points to solve the problem:

• Make sure that you use paper that meets our specifications.
  Please refer to the FAQs "What kind of paper can I use?" and "What is the recommended paper?"
   
• Choose Thick Paper mode in the printer driver.
  Or use thinner paper than you are currently using.
   
• Check the machine's environment. Conditions such as high humidity can cause hollow print.
  Please refer to Safety and Legal Guide or Product Safety Guide available on the Manuals section.
   
• The drum unit may be damaged. Put in a new drum unit.
  Please refer to the FAQ "Replace Drum".