Fig. 1
      1.- Correct diaphragm travel can 
      be obtained by adjusting the Return Check contact screw, in or out, until 
      the overall, length dimension of the contact screw and plunger is 15/16". 
      (See Figure 1). If the Return Check is already mounted on the carburetor, 
      make sure that the throttle lever is not bearing upon the end of the 
      contact screw as this might possibly depress the diaphragm slightly. When 
      turning the contact screw to arrive at the 15/16" length dimension, the 
      plunger must not be allowed to turn, otherwise the diaphragm may be 
      damaged. The plunger shaft incorporates two opposed "flats" upon which a 
      5/16" wrench may be placed to prevent turning, while the contact screw is 
      turned with a 3/8" wrench.
      2. - When installing the Throttle 
      Return Check on the carburetor the extra length attaching screws (1" long) 
      must be used to insure adequate thread depth. With the mounting bracket 
      securely tightened in place make sure that the head of the contact screw 
      squarely lines up with the throttle lever. To obtain correct alignment, it 
      may be necessary to slightly bend the mounting bracket. Caution - Bend 
      only the bracket, not the Return Check housing.