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| DEPTH CHARGES MARK 6 and MARK 7 | 
| PART II | 
| CHAPTER VI - REPAIRING AND OVERHAULING | 
| 
     OVERHAUL BOOSTER EXTENDER  | 
  
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     19. Faulty operation of a booster-extender is usually caused by leaky bellows or joints, or faulty action of the locking slide mechanism.  |