Hewlett Packard Q6651-60068 Hard Disk Drive for DesignJet Z6100 plotter.

Q6651-60068 Hard disk drive assembly, New Genuine OEM - Includes holder and screws. Replaces Q6651-60352 
Located behind the plotter, towards the right side, inside the power supply cover.

Hard Disk used in all of these HP DesignJet Plotter models:

DESIGNJET Z6100 PHOTO PRINTER 42
DESIGNJET Z6100 PHOTO PRINTER 60
DESIGNJET Z6100PS 42-IN PRINTER
DESIGNJET Z6100PS PHOTO PRINTER 42
DESIGNJET Z6100PS PHOTO PRINTER 60
Designjet Z6100 42-in Printer
Designjet Z6100 60-in Printer
Designjet Z6100ps 60-in Printer

Hard Disk Drive is implicated in these system errors:

8 Beeps during startup
Printer's Power-Up process stops when the front panel is displaying the number 17,
Error Code 06 displayed on the front panel
Error Code 06:10
Error Code 06:03
Error Code 08:11
Error Code 76:03
Error Code 79:04

NOTE:  You MUST NEVER replace both the Hard Disk Drive and the Ink Supply Tubes and Trailing Cable at the same time.