HP Laserjet 4000 Easter Egg - Print Hidden Credits Page

Summary:
Activate the service menu (instructions below)
Set diagnostics = ON
Return to the printer state to: Online
Use the Item + / - until the display says "Diagnostics test"
Press the left side of the Value + / - Key
The printer will print a special page.

Note: Diagnostics mode turns back to off after the page prints.

Specifics:

To get to the service menu, activate service mode by:
Turn off the printer
Press and hold Select and Cancel
Turn on the printer, keeping select and cancel depressed until all three lights remain lit.
Release select and cancel
press the right side of the menu key
press select to activate service mode.
Use the menu keys to select the service menu. Set diagnostics = on.
Press GO to exit service mode and return the printer to an online state.