JLG 3507 Supplemental Repair Manual page 104

ASSEMBLY
7
FIGURE 22: Release the check unit (7) by giving a hammer
blow to the external ring.
Introduce pressure again and check that at the end of piston
stroke, the check unit (7) is actually engaged onto the rod (6).
102 Dana Holding Corporation ASM-0025E - 212 Axle Service Manual