TM 5-4220-231-14&P (6) Remove tube    (18)   from    positionable elbow     (17)   by   positioning a   wrench on   the   union    nut  (19)   and   elbow    (117). Turn union nut     counterclockwise. 20 Remove, cut, and discard O-ring (20). 19 17 18 (7) Loosen and remove panel nut (7) from housing (8) at    front of    panel. Remove regulator housing (8)    from rear of  front panel. (8) Remove the three positionable elbows (10,13, and 17) from the 28 regulator housing (8). Remove, cut, 10 and   discard O-rings (28,29, and    30) from the    elbows. 8 29 30 17 13 b. Relplace 28 10 (1) Lubricate O-rings (28), M83248/2- 904; (29), M83248/2-904, and (30), 29 M83248/2-908, with silicone compound (item 9, Appendix D). Install    O-ring (28)    on   elbow (10),    0- ring    (29)    on    elbow (13),   and O-ring (30) on elbow (17). Install each 30 11 ' -,-- 4b elbow   on   regulator (8). 13 17 4-8