TM   10-3930-638-24&P 2-43. SERVICE BRAKE MAINTENANCE (cont) c. Hydraulic Brake Valve (cont). (2)  Power  Assist  Unit  (cont). STEP LOCATION ITEM ACTION REMARKS CLEANING  (cont) 6 All parts Clean Use  cleaning  solvent  P-D-680.  Dry  parts except breather filter (33), with com- pressed  air 7 Internal metal parts Flush After  cleaning,  remove  all  traces  of  clean- ing solvent by flushing with clean hydraulic  oil INSPECTION 8 Springs (14 and 25) Inspect Replace if cracked, distorted or broken 9 Spring (17) and shim(s) Inspect Replace  power  assist  unit  if  cracked  or (18) damaged 10 Cap screws (3), lock Inspect Replace if cracked, worn, or threads washers  (4),  body  (5), damaged, or body bore scored, pitted end plug (15) and or burred gland (2) 11 Push rod (7), spool (9), Inspect Replace if cracked, scored, pitted or piston  (10),  spool  cap burred (11) and poppet (19) REASSEMBLY/REPAIR 12 Body  (5) a. Breather filter (33) Install In breather hole of body (5) b. Retaining ring (32) Install Push into breather hole until ring (32) is against shoulder of hole C. Body (5) Lubricate Lightly coat bore at rear of body with hydraulic  oil d.  O-ring  (31) Install In seal (30) e. U-cup seal (30) and Install In groove of bore at rear of body (5), O-ring  (31) with lips of seal (30) facing body f. Backup ring (29) Install Push against flat side of U-cup seal (30) in body bore 13 Spool (9) and a. O-ring (26) Install In U-cup seal (27) cap(11) b. Spool cap (11) Lubricate Lightly coat open end of bore with hydraulic  oil c. Backup ring (28) Install Push against flat side of seal (27) in spool cap  bore 2-306