"ACTUATOR UNIT; 20-22 BAR +5V/-5V POWER SUPPLY; CONSISTS OF SIX ACTUATORS, ONE END WALL AND ONE CONNECTION WALL; THE CONNECTION WALL MAY IN SOME CASES BE REPLACED BY A PRESSURE REDUCER; THESE UNITS ARE MADE UP INTO A BLOCK BY TWO DRAWBARS; THE ACTUATORS ARE ELECTRO-HYDRAULIC AND WORK WITH MECHANICALLY RESET POSITION CONTROL; THE ACTUATORS MUST NOT BE UNSCREWED AND ARE THEREFORE LEAD-SEALED; IT FOLLOWS THAT A FAULTY ACTUATOR MUST BE REPLACED AS A COMPLETE UNIT"