Epson Stylus Pro 4000 Field Repair Manual page 171

Stylus Pro 4000 Field Repair Guide 4/28/05
6. Using a lens, inspect the printed pattern.
The pattern should look like this
Move this lever down to rotate the Print Head clockwise.
7. Adjust, and reprint, until the alignment pattern is correct.
8. Tighten the 4 Screws, and reprint the pattern to verify that the pattern is still correct.
9. Re-install the Carriage Cover.
Print Head Slant Adjustment (CR) Printer Component, Software Item, LCD Display, Printer Button Page 171.