HP Designjet 5100 Printer series - Manual (Page 51)

3-7
Maintain the ink system
HP Designjet 5100 printer Customer Reference Guide
7 Lift up the cover. This will now give you access to the printheads.
8 To remove a printhead, lift up the blue handle.
9 Place your index finger through the loop of the blue handle.
10 Gently pull the blue handle upward until the printhead is released from the
carriage assembly.