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Smoke Unit - Repair Tips From David Dewey
      Non-functioning smoke units are common. Sometimes it's a simple
      solution: Spray some WD-40 down the stack, let it soak a bit, then 'turn up
      the power' and see if it will start smoking. This works if the problem is
      gelled smoke fluid plugging the wick. If this doesn't work, then it's
      possible the heater unit is bad or the wick has burned or broken or you may
      only have a spider nest in the choo choo unit. This requires dismantling the
      loco, unsoldering the wires to the smoke unit and measuring the resistance
      (35-45 Ohms is within fac. specs.) If this measures OK, try the spray method
      again (Different people try different fluids, you want a solvent that will
      'cut' the smoke fluid, but won't start a fire!) Also check to see if you can
      blow air through the unit, sometimes a spider will build a nest at the
      Choo-Choo chamber opening. If none of these work, then it's time to replace
      the wick and heater, not an expensive job, but one that requires care (and
      in my situation, a pair of magnifiers!)
     Note: While rebuilding your smoke unit, it may be wise to clean the piston
     chamber and the piston. A non-lubricating  'tuner cleaner' is useful,
     although other solvents may be used. Follow the warnings on the product
      container! The piston is self-lubricating, and addition of lubrication here
      may gum up 'da woiks' slowing down your locomotive!
      Hmm, OK, I'll try to give a description of the operation, if I forget
      anything someone else on the list will point it out!
      First, I like to remove all the solder on the smoke unit wiring lugs
      (this is true for both versions, BTW, these instructions are for the SIB
      versions) The heater wire will not solder, it is just wrapped around the
      lugs, and you will be able to see that with the solder removed. Unwrap the
      wires so they are free from the lugs, you may now unscrew the top and lift
      it off without disturbing the 'guts'. There are two versions of this smoke
      unit; by this point in time, either can be found in any loco, if they have
      ever been repaired or replaced. One version has a separate bottom piece
      (which usually leaks!) and the heater is crosswise to the wheels (we'll call
      this one A); the other version has a cast bottom and the heater is parallel
      with the wheels (we'll call this one B). In either version, the heater is
      insulated from the unit body with a cardboard liner, which can be fragile!
      Now that the top is off, inspect the unit to see what happened. (If you had
      no Ohm reading, obviously the wire is broken somewhere, if you had a
      reading, it's likely the wick will be burnt). Also look for a little white
      spider nest in the chamber between the choo choo sound plate and the body.
      If you had a good ohm reading, and the wick isn't burnt, but you find the
      nest, you can probably reassemble the unit (well, ya gotta get rid of the
      nest first!)!
      On the B version, all the guts will just lift out, with care. On the A
      type, it's best to remove the bottom cover, pry out the wick, and cut it off
      where it goes through the casting to the top chamber, you can then carefully
      lift out the heater from the top. On the A type, the cardboard may stay
      inside the body, that's fine, just leave it there!
      On both versions, blow through the piston area to see if you get 'choo'
      (you'll have to use your finger as a 'cover' for the little choo-choo
      chamber) and that the small hole into the chamber is clear. The cardboard on
      the A type can sometimes shift and cover the hole. Clean out the unit, you
      may want to lightly sand the sealing surface by placing it against a flat
      surface with some fine (600 grit or finer) sandpaper (Auto paint stores have
      this to 2000 grit) but this is only if you find it corroded.
      The new wick/heater must be handled carefully, you don't want any of the
      heater wire crossing over itself, or it will burn out quickly, if not
      immediately! If you are working on a type A unit, you will want the wick
      ends to be stiff, some come with a 'glue' already on them. This is so you
      can start them through the tiny holes in the bottom of the heater chamber!
      If your wick isn't glued on the ends, you can do this yourself with some
      white glue (maybe gel type super glue, I haven't tried it--but you don't
      want the glue traveling up the wick!) or, with patience, I have just twirled
      the ends in my mouth like a painter setting his brush--if you can get the
      wick to come to a point so you can guide it through the hole, that's all you
      need.
      OK, A type repair: Wick is started through both holes, carefully pull
      both sides through until the heater element is centered in the chamber area.
      You don't want it against the bottom, nor near the top, either spot will
      cause failure; one burns the cardboard, the other burns the lid! (That's
      what makes that bulge in the cover seen on some units.) Ideally it is just
      in the air stream from the piston chamber. Use a magnifier and check that no
      wires are crossed! Cut off the glued area of the ends and coil the wick in
      the bottom chamber, it will fill it! Here's where I 'cheat' a bit; I use a
      very small amount of 'gasket in a can' to seal the bottom chamber, as I
      can't seem to get the factory gaskets to not leak! A leaky unit will oil
      your rails, but it's not the right kind of oil!! See Roger Hinds for the
      rail oil--disclaimer, I have no economic interest in this 'plug'!. Back
      to the repair:
      B type: cut your old wick and remove it from the cardboard chamber, thread
      the new wick through the holes, and as in the A type, center the wick so it
      isn't too high or too low. Coil the wick ends in the unit and check to see
      that there is room for the cardboard chamber to fit, and for air to pass
      through the chamber, you may have to cut off some of the wick to do this.
      Again, look for crossed wires.
      Both: Now you can fit the cover on, I like to add some smoke fluid at this
      time, to 'prime' the wick. Feed the wires through the lug holes, check that
      nothing changed while placing the cover on (This is sort of like looking to
      see if the refrigerator light goes out!). Tighten the screws (you may use a
      little gasket stuff here too, if you're game). Check the coil Ohm reading,
      if it's OK, then wrap the wires around the lugs, resolder and test.
      If you did everything right, you will have a smoke unit that now will
      chase everyone out of the room!
      Trust me; the job becomes easier with practice!
      S'incerely,
      David Dewey
      Watch the Railroad watch and repeat after me, "The future is in S, the
      future is in S, the future is in S, the future...."