TM10-3930-660-34 16-21.  PISTON PUMP - REPAIR (Cont’d) NOTE The rotating group (18) consists of components (11, 14, 16, 17, 19-25). f. Hold shoe plate (19) with both hands to prevent rotating group parts from separating during removal, then remove rotating group parts (18) from pump housing (6). g. Remove pin retainer (24) from cylinder block (17). h. Remove piston (7) from housing (6). 3. DISASSEMBLE CYLINDER BLOCK ASSEMBLY. WARNING Spring (20) located in the cylinder block (17) is under high tension and can cause severe personal injury if retaining ring (21) is not removed correctly. a. Place flat washers (A), as required, under head of capscrew (B).  Slide capscrew (B) through retaining ring (21) and spring (20) until threaded end of capscrew is visible through hole on other side of cylinder block (17). b. Place additional flat washers (A), as required, and nut (C) on threaded end of capscrew (B). c. Carefully tighten nut (C) and capscrew (B) until spring tension is removed from retaining ring (21). NOTE Use care when handling close tolerance parts that are removed in steps d and e, to prevent burrs from forming. 16-130