TM   9-2350-256-34-1 WARNING Do  not  attempt  to  disassembly  or  repair fuel   control   valve   unless   facilities   are available   to   conduct   the   flow   test described  in  paragraph  3-36b(1)(h).  An improperly calibrated valve can cause ‘ex- cessive fuel to build up in and around the heater  assembly,  creating  a  fire  hazard. a.   Remove   mounting   bracket   (2)   by removing four screws (1) that secure it to the valve body (18). b.  Remove  three  screws  (3)  and  remove the  outer  plate  (4),  insulator  plate  (5),  preformed packing  (6),  3-hole  plate  (7),  and  restriction  orifice plate  (8).  Pull  three  small  preformed  packings  (9)  out of  recesses  in  valve  body. CAUTION Handle the orifice plate with care. Do not drop  it.  Do  not  force  any  object  through the  orifice  plate  openings.  The  slightest distortion in the plate or orifices will in- terfere  with  proper  operation  of  the  fuel control valve. c.  Remove  adjusting  screw  (21)  and spring  (22).  Remove  four  screws  (20)  and  remove diaphragm  cap  (23),  diaphragm  assembly  (24)  and preformed packing (25). Unscrew valve core (19) and remove  it. d.  Remove  restriction  solenoid  and  valve assembly   by   removing   screw   (32).   Pull   out   coil assembly  (31)  and  washer  (30).  Remove  three  screws (33) in bottom of solenoid cup (29). Remove solenoid cup  and  pull  out  sleeve  and  core  assembly  (28), gasket (27), valve spring (26), and plunger assembly (34). Remove valve seal (36) from bottom of plunger (35). e. Repeat d above to disassemble shut-off solenoid  and  valve  assembly,  except  pull  out  coil assembly  (10)  instead  of  coil  assembly  (31). f. Remove bleed valve stem (37) and inlet screen (38) and valve body (18). g.  To  remove  thermostat,  unsolder  wire (14) from the electrical terminal on the valve body. Slide off the insulating sleeve (13) and the insulator (12). Remove two screws (15) that secure the ther- mostat  (17)  to  valve  body,  and  remove  the  ther- mostat.  If  the  thermostat  is  being  replaced,  un- solder  the  cable  assembly  (16)  from  terminal  on  ther- mostat. h.  Unscrew  elbow  (11)  to  remove  it  from valve body (18). (7) Ignition control (fig. 3-10.2). (a)  Loosen  the  two  Dzus  fasteners  which secure  the  guard  assembly  (16)  to  the  top  of  the heater;  remove  the  guard. (b)  Cut  the  two  cable  assembly  straps  (37) which  bundle  the  wires  together.  Disconnect  the igniter  lead  and  the  voltage  limiter  lead  from  one end  of  the  ignition  control  (25).  If  necessary  to provide access to the wires, remove the fuel control valve ((6)(b) above). (c) Disconnect  the  ignition  control  lead  from one of the NO contacts on the flame detector switch (21). Remove the two screws (17) on the outer edge of the  ignition  control,  and  loosen  the  two  remaining screws. Pull off the ignition control. (8) Burner assembly (fig. 3-2). (a) Remove blower assembly ((1) above). (b) Loosen the two fasteners which secure the electrical inlet assembly (36) to the heater housing (28), and swing it out of the way. (c) Remove the igniter (9) as described in (3) above.  Remove  the  seal  (35)  from  the  top  of  the heater  housing. (d) Remove  the  screw  (4)  which  secures  the igniter tube and bracket (8) to the secondary blower housing (3) and pull out the tube to remove it. (e) Disconnect fuel tube (5) by loosening com- pression nuts (6) at fuel control valve (26) and at bur- ner (10); pull out tube. (f) Slide  secondary  blower  housing  (3)  out  of heat  exchanger  assembly  (15). (g)  Remove  six  screws  (39)  that  secure  the burner (10) to heat exchanger, and pull out burner. (h) Refer to figure 3-10.5 and disassemble the burner  as  follows: Legend for fig. 3-10.5: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Nut Nut Washer Plate and bushing assembly Yarn  wick Washer Washer Washer Fuel  vaporizer Washer Washer Fuel  vaporizer  shield Screw Burner cup and stud assembly 3-18.8 Change 2