TM 10-3930-659-34 5-9.  TRANSMISSION CONTROL VALVE MAINTENANCE (Con’t). 18. Apply a light coat of lubricating oil to piston (58) and valve block (31) bore. CAUTION Ensure  that  clip  is  installed  in  groove  of  piston  and  In  slot  inside  the  face  of  valve  block.  Shift control of clutch will fall to operate if clip Is Improperly Installed. 19. Install piston (58) in valve block (31) with clip (59). 20. Install spool (60) in valve block (31). 21. Install washer (67) tight against inside of cover (62). 22. Install new shaft seal (66), washer (65), and new retaining ring (64) on cover (62). 23. Install new preformed packing (61) and cover (62) on valve block (31) with two screws (63). 5-73