Oki ES 1624n MFP - Manual (Page 79)

Replacing Consumables • 79
9. Use the LED lens cleaner supplied with the new toner cartridge
to gently wipe the surface of the LED head which corresponds
to the color toner cartridge you are replacing:
10. Close and latch the top cover.
CAUTION!
Do not use methyl alcohol or other solvents on the LED
head: damage to the lens surface will occur.