TM  10-3930-643-34 HYDRAULIC  SYSTEM  TROUBLESHOOTING  AND  MAINTENANCE.  (cont) 12-7. Boom Assembly Valve. (Sheet 5 of 6) CLEANING/INSPECTION   (cont) NOTE All grooves and  passages  in housing must be free of foreign matter. 15. Inspect all parts. Refer to para- graph 2-9. ASSEMBLY 16. 17. 18. 19. NOTE Lubricate  all  preformed  packings, wipers,  seals.  sliding  parts  and housing  before  installing. Install  new  preformed  packing  (24)  on poppet (25). Install ring (22) and new preformed packing (21) on spacer (23). Using an 11/16” box and open end wrench, install items 23 thru 21 as an assembly and nut (20) on poppet (25). Install spring (18) and items 25 thru 20 as an assembly in plug (19). Go to sheet 6 12-54