HP Designjet 4020 and 4520 Printer Series - User's Guide: English

4. Locate the carriage.
5. Pull up and release the latch on top of the carriage.
6. Lift up the cover. This will now give you access to the printheads.
7. To remove a printhead, lift up the blue handle.
ENWW Remove a printhead 93
Ink system