Apple Macintosh Performa 577 - Manual (Page 159)

Adjustments Yoke - 38
5 Hold the plastic yoke
collar in position and
carefully tighten the
yoke clamp screw so that
the collar cannot slip. Do
not overtighten the
screw.
6 Replace the rear
housing and switch on
the computer.
7 Verify that the top and
bottom edges of the
picture are parallel with
the top and bottom of the
bezel.
Yoke Clamp
Screw
Plastic Yoke Collar