Dell 5210n Mono Laser Printer User Manual page 97

NOTE: If an option card has been installed, you may need to remove the option card before installing the Font ROM.
2. Unpack the Font ROM.
NOTICE: Font ROMs are easily damaged by static electricity. Touch something metal such as the printer frame before you touch a memory card.
3. Holding the Font ROM by the locking clips, align the plastic pins on the card with the holes on the system board.
4. Push the Font ROM firmly into place, and release the locking clips.
The entire length of the connector on the Font ROM must touch the system board and be locked into the connector.
Be careful not to damage the connectors.
5. Close the side door.
Removing Font ROMs