JLG 660SJ Service Manual - Manual (Page 171)

SECTION 4 - BOOM & PLATFORM
3121298 – JLG Lift – 4-23
11. Before removing piston (3), mark housing (1) ring gear in
relation to piston O.D. gear. There should be timing
marks on housing (1) ring gear, piston (3), and shaft (2).
12. To remove piston (3), use a rubber mallet and plastic
mandrel so piston is not damaged.
13. At the point when piston gear teeth come out of
engagement with housing gear teeth, mark piston and
housing with a marker as shown.
14. Remove O-ring (204) and backup ring (207) from end
cap (4) and set aside for inspection.