HP Laserjet 4000 and 4050 series service mode

HP Laserjet 4000 and 4050 series service mode
1 Hold down [Select] and [Cancel Job] while turning on the printer until all of the lights on the Control Panel are lit. (If the Control Panel reads INITIALIZING, the keys were released too soon.)
2 Press the right side of the [Menu] key, then press [Select]. The message SERVICE MODE is displayed.
3. Press [Menus] once to display SERVICE MENU.
4. Once it says SERVICE MENU press ITEM to scroll through service mode items.
5. To exit the Service Mode press [Go].