Epson Action Laser - Manual (Page 134)

Maintenance Messages
9. Store the developer cleaner, which was also packed with the
drum, in a safe place for future use. You need to use the
developer cleaner to clean the developer unit if vertical white
lines appear on your printed page. (The General Printer
Maintenance section of this chapter has details.)
Before reinstalling the basket with the new drum unit in your
printer, be sure to perform the cleaning procedures described below.
Routine cleaning
There are certain printer components inside the printer you must
clean each time you replace the drum unit. See the following section
on printer cleaning.
6-18 Maintenance and Transportation