TM10-3930-660-34 16-21.PISTON PUMP - REPAIR (Cont’d) 8.  ASSEMBLE ROTATING GROUP PARTS. WARNING Spring (20) can cause severe personal injury if retaining ring (21) is not properly installed.  Use capscrew (A), flat washers (B),  as required,  and nut (C) to temporarily relieve pressure of spring (20) when installing retaining ring (21). NOTE Use care when assembling parts in cylinder block to prevent burrs from forming. a.  Install spring (20),  spring washer (23),  and spring washer (22) in cylinder block (17). b.  Place flat washers (A),  as required,  on hex end of capscrew (B).Insert capscrew (B) through spring (20) until threaded end of capscrew is visible through hole on other side of cylinder block (17). c.  Place additional flat washers (A),  as required,  and nut (C) on threaded end of capscrew (B). d.  Carefully tighten nut (C) and capscrew (B),  and install retaining ring (21). e.  Slowly and carefully loosen nut (C) and capscrew (B) until pressure of spring (20) is on retaining ring (21).Remove capscrew (B),  flat washers (A), and nut (C) from cylinder block (17). 16-140