lock   ratchet   by   moving   the   hook-driving   shaft   to the   right   until   it   clears   the   hook-driving   shaft   lock ratchet,   thus   allowing   it   to   drop   from   the   shaft. Arm   Shaft   Connection   Belt   Timing Collar   and   Hook-Driving   Shaft Ball-Bearing    Collar The   arm   shaft   connection   belt   timing   collar and   the   hook-driving   shaft   ball-bearing   collar   are the   initial   timing   points   on   the   machine.   Do   not remove  these  parts  from  the  machine.   In   machines fitted  with  cast  iron  bushings,  the  timing  collar will  fall  off  as  the  shaft  is  withdrawn. Hook-Driving   Shaft The   hook-driving   shaft   (figure   4-6   [N]) transfers   power   and   motion   to   the   units   attached to   it.   To   remove   the   hook-driving   shaft,   you   grasp it   and   withdraw   it   to   the   right. Bobbin-Case   Opener The   bobbin-case   opener   (figure   4-9   [D])   acts as  a  lever  to  pull  the  bobbin  case  back  from  the throat  plate.  It  allows  the  needle  thread  to  pass between   the   bobbin   case   and   the   throat   plate.   To remove   the   bobbin-case   opener,   you   unscrew   the adjusting   screw   (figure   4-9   [E])   and   lift   it   from the   hook   saddle   assembly. Hook  Saddle  Screw The  hook  saddle  screw  (figure  4-6  [B])  holds the   hook   saddle   assembly   in   place.   Unscrew   the hook   saddle   screw   to   remove   it. Hook   Saddle   Assembly The   hook   saddle   assembly   (figure   4-6   [U]) forms  the  lower  half  of  the  stitch.  To  remove  the hook  saddle  assembly,  unscrew  the  hook  saddle screw   and   loosen   the   hook   saddle   pinch   screw (figure   4-6   [A]).   Draw   the   hook   saddle   assembly slightly   toward   the   operator,   slide   it   to   the   left until   it   clears   the   center   hook-driving   shaft bushing,   and   withdraw   it   from   the   machine.   This completes  the  disassembly  of  the  sewing  machine. REASSEMBLY Before   reassembling   the   sewing   machine,   you will   need   some   grinding   compound   to   smooth parts   that   may   have   surface   rust   or   small   burrs. A   small   amount   of   grinding   compound   on   the surface   is   sufficient.   Rotate   the   two   parts   until they   move   freely.   You   will   also   need   some   10W mineral   oil   to   lubricate   all   moving   parts.   After you   accomplish   these   tasks,   proceed   as   follows to   reassemble   the   sewing   machine. Hook   Saddle   Assembly To   replace   the   hook   saddle   assembly,   hold   it in   an   upright   position   with   the   saddle   clamp facing   the   bed   of   the   machine;   then   place   the saddle   clamp   on   the   edge   of   the   center   hook- driving   shaft   bushing.   Swing   the   hook   saddle assembly   toward   the   bed   of   the   machine   and   slide it  to  the  right  and  into  place  in  the  opening  in  the casting. Hook   Saddle   Screw With   the   hook   saddle   assembly   as   far   to   the right  as  it  will  go,  replace  the  hook  saddle  screw and   tighten   it. Bobbin-Case   Opener Lift   the   machine   to   the   upright   position. Replace   the   bobbin-case   opener   so   that   the   curved end  points  toward  the  bobbin  case.  Replace  the bobbin-case  opener  adjusting  screw  and  tighten  it. Hook-Driving   Shaft Tilt   the   machine   forward.   In   replacing   the hook-driving   shaft,   you   should   note   that   it   has five   splined   grooves.   One   of   the   splined   grooves is  located  at  one  end  of  the  shaft.  Insert  the  end without   a   splined   groove   into   the   right   hook- driving   shaft   bearing. Hook-Driving   Shaft   Lock   Ratchet As   the   hook-driving   shaft   is   pushed   toward the   left,   or   face,   of   the   machine,   replace   the   hook- driving   shaft   lock   ratchet   so   that   the   flange   with the  setscrews  faces  the  left  of  the  machine. Feed-Driving   Connection and   Feed-Driving   Crank Hold   the   feed-driving   eccentric   with   the   flange and   spring   to   the   right;   then   place   the   feed-driving connection,   with   the   feed-driving   crank   attached, over  the  cam  on  the  feed-driving  eccentric.  Be  sure the   oiling   felt   faces   upward   and   the   crank   is toward   the   operator. 4-27