TM 9-2350-256-34-1 paragraph  3-33c(4)  and  remove  this  switch  h-em heater. (1) Next, remove the adjusting screw and pivot the  microswitch  on  its  bracket  to  provide  access  to the  ceramic  rod.  Invert  the  flame  detector  switch assembly  and  remove  the  ceramic  rod. (2)  With  the  switch  assembly  inverted,  rap  on the side of the tube with a screwdriver blade to jar loose  oxides  and  dirt.  Continue  rapping  until  no more oxides fall out of the tube. h.  To   clean   the   overheat   switch,   refer   to paragraph 3-33c(5) and remove this switch. (1) Clean the points by sliding a piece of clean white bond paper between them. Use a soft bristle brush  to  brush  off  loose  dust  and  dirt. CAUTION Do  not  use  sandpaper,  emery  cloth,  or other  abrasive  material  to  clean  switch points. i. Clean all electrical components and nonmetallic parts with a clean cloth. Remove greasy and gummy deposits  with  cleaning  solvent.  Clean  all  metallic parts  with  a  cloth  dampened  with  solvent. 1 3-35. Inspection and Repair a.  Air  Control  Assembly,  Deflector,  and  Exterior Components. (1) Inspection (a) Inspect  air  inlet  hose  for  fraying,  cracks and  other  signs  of  excessive  wear. (b) Inspect heater for any damage that would impair its use. (c)  Inspect  fuel  filter  for  leaks,  cracks,  and other  damage  that  would  impair  its  use. (d) Inspect  copper  tubing  for  cracks,  dents, obstruction and other signs of excessive wear. (e) Inspect  seals  for  cracks,  tears,  hardening and  other  signs  of  excessive  wear. (f) Inspect threaded parts for nicks and cross threading. (g) Inspect  saddles  on  bulkhead  for  cracks, breakage,  and  other  signs  of  excessive  wear. (h) Inspect  all  metal  parts  for  cracks  distor- tion, open weld seams and other damage that would impair its use. (2) Repair. (a)  Repair  damaged  threads  with  a  thread chaser,  if  practical,  or  replace  threaded  parts  that are  defective. (b)  Weld  open  seams  and  other  damaged areas of metal parts if practical (TM 9-237). Replace defective  metal  parts  not  repairable  by  welding. (c) Replace all other defective parts. b.  Personnel  Heater  Components. (1) Blower assembly (fig. 3-10.3). (a) Inspect  blower  wheels  for  cracks,  distor- tion,  and  bent  or  broken  blades.  Replace  if  damaged. (b) Inspect all wiring for broken or burned in- sulation,   damaged   terminals,   or   broken   wires. Replace  damaged  wiring. (c)  Test  the  resistor  for  continuity,  and  in- spect the ceramic insulator for cracks, burned areas and other damage. Replace the resistor if it is open circuited or damaged. (d)  Inspect  the  voltage  limiter  for  cracks, distortion, signs of overheated components, or other damage,  Replace  if  defective.  Test  the  voltage limiter  as  follows: 1. The following test equipment is required: a.  24  volt  dc  power  supply,  5  ampere minimum capacity. b. Two on-off switches. c. Two resistors, 50 watt minimum, one 6 ohm and one 10 ohm. d. Two 0 to 30 volt dc voltmeters. NOTE The voltage limiter can be tested while it is still installed in the assembled heater. Just make sure that the heater housing is connected  to  the  same  ground  as  the meters and resistor, and perform the test as  described  below. 2. Connect test equipment as shown in test schematic, figure 3-10.6. Change 2 3-18.11