IBM PCjr Hardware Maintenance And Service page 115

The problem with your IBM Color display may be that
the characters on the screen are the wrong size (vertical
size not properly adjusted).
LIST
OAD SAV
CON
Too Short
Too Tall
ARE THE CHARACTERS THE CORRECT SIZE?
Go to Section 4, "Removal/Replacement and
Adjustments," and perform the IBM Color
Display Vertical Size Adjustment. Then go to
page 3-500-28.
Display 3-500-27