JLG 1200SJP Service Maintenance Manual page 260

SECTION 4 - BOOM & PLATFORM
44. Pull the fly boom extend cables out enough to have
clearance to remove the sheave, and remove the retain-
ing bolt, keeper pin, pin, bushings, and sheave from the
front of the outer mid boom section.
4-26
NOTE: When pulling the fly boom section out of the outer mid
boom section, make sure the fly boom retract cables do not
catch at the rear of the boom section.
45. Attach a lifting device to the fly boom section and pull
the section and fly boom extend cables from the outer
mid boom section. Secure the rear of the outer mid
boom section so it doesn't move when the fly boom sec-
tion is withdrawn.
– JLG Lift – 3121142