TM 10-3930-669-34 13-2.        MAST    ASSEMBLY    REPLACEMENT/REPAIR (CONT). WARNING Use care when removing or installing snap  and  retaining  rings.    Snap  and retaining rings are under spring tension   and   can   act   as   projectiles when released and could cause severe eye injury. (25) Remove two retaining rings (74) from secondary cylinders (75 and 76). WARNING • Secondary  cylinders  weigh  140  lbs  (64  kg)  each.    Attach  suitable  lifting  device  prior  to removal to prevent possible injury to personnel. • All personnel must  stand  clear  during  lifting  operations.    A  swinging  or  shifting  load  may cause injury or death to personnel. (26) Remove two secondary cylinders (75 and 76) from outer rail (61). 13-14