Lexmark C912 Service Manual - Page 272

5055-xxx When replacing the LED printhead, replace the corresponding EEPROM shipped with the printhead, on the printhead controller board. Place the printer in Diagnostic Mode, input the printhead light quantity value plus eight (refer to note below) from the printhead label. Be sure to remove any fingerprints or stains from the printhead lens. The positioning pins at the both ends of the printhead are fixed with hexagon nuts. Do not loosen or remove either nut, as the image will unfocus. Note: Light intensity value = printhead label value plus eight. 7. For serial numbers XX-1XXXX and above: Disconnect the affected LED printhead connectors from the printhead controller board. Remove the screw from the ground wire located on the LED printhead. C912 S/N's XX-1XXXX 8. Remove the LED printhead and the cables from the printer. When replacing the LED printhead, replace the corresponding EEPROM shipped with the printhead, on the printhead controller board. 4-26 Service Manual