The 2018 uses a pellet type smoke unit. The white residue you see is the remnants of previous pellets.

If the smoke unit is not too clogged, power up the engine and lock it in neutral. Turn the power all the way up, and the residual smoke pellet material will start to melt into the smoke element. Use a toothpick to gently scrape any material that may be in the stack into the element.

For a heavily clogged smoke unit, the locomotive shell will have to be taken off, and the smoke unit disassembled. Then any excess pellet material can be gently cleaned out of the smoke unit and off the heater element.

Larry