HP 8566B Adjustment Manual page 208

4. Final Display Adjustments (SN 3004A and Above)
17. Adjust AlA2R512 ORTHO and the front-panel ALIGN control
to optimize the orientation and appearance of the rectangular
graticule pattern on the CRT display.
18. Repeat steps 13 through 17 as needed to optimize overall display
focus and appearance.
3-66 Adjustments