TM 9-2920-243-34 c.   Shift   Housing   Assembly. (1)   Inspect   shift   housing   for   cracks   or distortion  and  burs  on  mating  flange  and  packing surfaces.  Replace  if  damaged. (2) Inspect bushing-type bearing for score marks and wear patterns. Check bearing against limits specified in repair rebuild standards (para 3-31e) and replace (para 3-15c) if worn beyond limits. (3) If the bushing.type bearing is removed from  the  shift  housing,  check  diameter  of  bearing bore  against  limits  specified  in  repair  and  rebuild standards  (para  3-31e).  Replace  shift  housing  if worn  beyond  limits. d.   Drive   Assembly. (1)   Inspect   bearing   surface   and   drive assembly internal splines for score marks and wear  patterns.  Replace  drive  if  worn  or  damaged. (2)   Check   drive   spring   against   limits specified  in  repair  and  rebuild  standards  (para  3- 31a) and replace spring if it is not within these limits. (3) Inspect drive collar for signs of wear and distortion and replace drive assembly if either condition  exists. (4)  Inspect  gear  teeth  for  wear  pattern  and replace  drive  assembly  if  wear  is  excessive. e. Brush   Holder   Assemblies   and   Brushes. (1)   Inspect   brush   holder   and   spring assemblies  for  any  visible  damage.  Replace  if damaged. Check brush spring tension with a 0 to 40  ounce  spring  scale.  It  should  require  ap- proximately 36 ounces to lift end of spring out of brush holder. If tension is less than 30 ounces, replace  holder  and  spring  assembly. (2) Inspect brushes for chips, cracks, loose terminal leads, and grease spots. Check length of brushes  against  limits  specified  in  repair  and rebuild standards (para 3-31a.). Replace brushes if worn beyond these limits. f.  Field  Ring  Assembly. (1)  Check  field  coils  for  insulation  breakdown with  an  ohmmeter.  Attach  one  probe  of  ohmmeter to field coil terminal and the other probe to field ring (fig. 3-25). The minimum reading should not be  less  than  one  megohm.  If  field  coils  are damaged,  replace  starter. (2) Inspect field frame for cracks and burs. Replace  starter  if  cracked. Figure 3-25. Testing field coils for grounds. g.  Armature    Assembly. (1) Inspect  commutator  contact  surface  of armature.  A  satisfactory  condition  is  indicated  by an  even,  highly  burnished,  dark-copper  color.  If contact  surface  is  rough,  pitted,  scored,  burned, or coated with hard carbon or oil, commutator must  be  cleaned  or  resurfaced  as  necessary, provided it is in good electrical and mechanical condition  as  a  result  of  following  inspection. Check  armature  against  limits  specified  in  repair and  rebuild  standards  (para  3-31  a) and  replace starter if it is not within these limits. Inspect splines  of  armature  shaft  for  wear  or  damage  and replace  starter  if  either  condition  exists. (2) Inspect armature for grounds with a test light by touching one probe to commutator bar riser and other to armature core (fig. 3-26). Test all commutator bars in this manner. If test light glows,  armature  is  grounded  and  starter  must  be replaced. (3)  Inspect  armature  for  short  circuits  with  a growler. Place armature in growler and hold a thin strip of steel, such as a hacksaw blade, about 1/32 to 1/16-inch away from armature core as shown in figure 3-27. While holding steel strip in position, rotate armature slowly in growler. A short  circuit  will  pull  the  steep  strip  tightly against  armature  core  and  cause  strip  to  vibrate. If  a  short  circuit  is  found,  starter  must  be replaced. 3-10