HP Designjet 4500 Printer series - Manual (Page 223)

If you have horizontal misalignment, you will see something like this:
If you have vertical misalignment, you will see something like this:
If you have bidirectional misalignment, you will see something like this:
Corrective action
1. Align the printheads, using the same paper type with which you were experiencing
unacceptable print quality, if feasible (some paper types are not suitable for printhead
alignment). See Align the printheads.
2. If there is no improvement in print quality, contact your customer service representative.
ENWW Interpret Image Diagnostics part 1 209
How do I... (Image
Diagnostics Print topics)