HP Latex L25500 Ink Tube System 60" CH956-67040 DesignjetZ6600 00000003 indicates the Black printhead

00000003 indicates the Black printhead has failed

The replacement procedure for this part is found in section 8-34 of the service manual --available here

This part fits the following 44" plotters:

Black ink cartridge for HP Designjet 500 and 800 plotters

01 (or equivalent)

HP Latex L25500 Ink Tube System 60" CH956-67040 DesignjetZ6600 00000003 indicates the Black printheadHP Latex L25500 60" Ink Tube System Rebuilt and Upgraded $100 Core Refund Final Price $665 CH956 67040 HP Latex L25500 Ink Tube System. We rebuild the tube system with all 40 seals upgraded to silicone, new printhead ports and check valves. Leak tested to 3x normal operating pressure. OEM tube seals oxidize, crack, and leak over time. LPS upgraded tube systems have LPS designed seals installed with an expected lifespan of at least 10 years. Ink tubes