Caution: Be sure that the lens is always well supported while
it is being removed. If it should drop, the projection-stage plate
glass, the Fresnel condenser lens, and possibly the rear surface
mirror would be broken, and the projection lens might be dam-
( 1) Remove the window (aabove).
(2) Remove the mirror housing by removing the three screws,
lockwashers, and nuts on the widerside of the support arm.
Lift off the mirror housing and lay it to one side.
(3) Support the lens with one hand. W i t h s p a n n e r w r e n c h ,
remove the projection lens by unscrewing the retaining ring
on top of the support arm. When the projection lens retain-
ing ring is free, lift it of and lower the lens through the hole
in the support arm.
(4) To reinstall the projection lens, perform the procedures given
in (l), (2), and (3) above in reverse order.
d. Support Arm.
(1) Remove the projection head assembly by racking it up off
the support post.
(2) Remove the projection lens (c above).
(3) To resassemble the projection head, perform the procedures
given in () and (2) above in reverse order.
e. Elevation Knob and Focusing Knob, To remove the elevation
knob, loosen the Alleen-head setscrew and like the elevation Knob off
the threaded stud. The focusing knob is attacthed to the pinion shaft
with a roll pin and cannot be removed.
Page 63, paragraph 58b. Add after the last sentence: On the PH-
637C/PFP, loosen the two hexagonal-head bolts on the upper location
bracket of the yoke (fig. 1.1), and move the support arm from side to
side until the top and bottom edges of the image are horizontal: then
tighten the hexagonal-head bolts.
Paragraph 59d(1) (page 14 of (2), second sentence. Add after
the second sentence : On the PH-637C/PFP, loosen the two hexagonal-.
head bolts on the upper locating bracket of the yoke.
Page 64, paragraph 59d)(2) (page 14 of C2), second sentence. Add
after the second senetence: On the PH-637C/PFP, raise the project ion
stage all the way.
Paragraph 59f( 3 ) ( p a g e 1 4 o f C 2 ) , l a s t s e n t e n c e , C h a n g e " P H -
637B/PFP to PH-637B/PHP and the PH-637C/PFP.