E-flite J-3 Cub 25 ARF - Manual (Page 21)

  6. Install the grommets and brass eyelets
into the aileron servo. Attach a 6" (152mm)
servo extension, securing it with thread or a
commercially available clip. Center the servo and
install a long servo arm onto the servo.
  7. Check to make sure you are using the correct
servo hatch for the wing panel. Simply place the
hatch in position to make sure the opening for the
servo horn aligns.
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