White residue on postwar smoke unit

looks like smoke pellet to me. probably try some mineral spirits. 

It disolves in hot water.

Normally there is a felt washer between the smoke unit and the body. Often it gets quite hard with smoke stuff, and won't even be recognizable as being felt. Any parts dealer should have replacements.

The last time I had to disassemble a smoke unit, I used an old hair dryer to heat it up, and soften the smoke material. Worked like a charm, it came apart easily. Should work to soften that build up on the outside of your smoke unit. (Looks to me like some fiberglass batting type material is stuck on the outside too)

Thanks guys! I always appreciate how knowledgeable everyone is on this forum!

If there is any residue on the locomotive shell, my postwar 2046 had an original sticker inside that said it can be removed with petroleum jelly and a soft cloth used sparingly.

I believe they used asbestos under the heating element inside the unit. the residue sticks to it. scrape the residue that is not on the insulation and reuse it. disolve the rest in water and dispose of it. on the outside should be the felt washer and residue

You might consider upgrading to the liquid smoke unit kit.  No pill mess and easy to install.  Price is not bad either.  Than you can have your train smoke smell like hot chocolate.

Steve, Lady and Tex

Don't do it.  All the element does is melt the pellets, so your existing smoke unit will work just fine with any smoke fluid.  The pellet types are much more reliable and last for decades - not so much if you go with a liquid type.  Try Mega-Steam fluid - it comes in dozens of aromas.

I'll take the "pill mess" over "smoke fluid mess" any day.

I appreciate that both are considered safe, but I'd rather deal with cleaning up pellet dust, as opposed to smoke fluid and its vapors.
To each their own!

Smoke pellets are available, as are all the parts for the pellet type smoke unit.

I use Mega-Steam fluid in my old Hudson that has a pill type smoke unit. It works perfectly and produces lovely puffs of smoke. 

my 736 & 2046 have the pill type which I use liquid in, and the 736 smokes great, as does my Marx steamers. My MTH M1a smokes great with the liquid unit. The only one hat makes a mess is my WBB J class and it's Seuth unit. slobbers all over the boiler.