Hitachi EX20UR-2 Manual page 289

9. Remove bushing (13) from cylinder head (11).
W506-04-02-009
10. Remove 0-ring (18), backup ring (9) from retainer
(19).
W551-04-02-008
8. Remove wiper ring (12) from cylinder head (11).
FRONT ATTACHMENT / Cylinder
W04-02-19