A toothpick is a great tool, but you must be careful when Going down into the smoke chamber. The smoke generator is inside that chamber and could potentially break the heating element with the point of the toothpick. Try using as well a q tip swab a little Vaseline petroleum jelly to clean off some of the white residue left behind from the used up smoke pellets around the smoke stack. It’s gentle and it work pretty good. But like the previous response you received, try burning off some of the old smoke pellet residue
by putting your 2018 Steam Locomotive in neutral, turn off the E-unit to silence the hum, and turn the power up. That should burn off any remaining smoke pellets left behind. At such time, it would be a good way to determine if the your locomotive if puffing smoke correctly. If so Great. If not, then you will have to check and see if the smoke lever is moving freely. If not, then then you will need to remove the shell, and see what might be either binding up, and if the smoke piston is moving up and down in its chamber. Also, it would be a good time to check and see if the smoke units air hole underneath it is unabstructed from any smoke pellet residue. You can clean that tiny hole with a toothpick without worry, then clean the smoke piston, the chamber it goes into, and make sure the smoke lever moves freely with the cross head. There’s a felt smoke stack gasket in between the smoke unit and the shell. Make sure that’s lined up correctly over the smoke stack as well when putting it back together. You don’t want to block the smoke when the train is running. The 2018 was originally built starting in 1956 - 1958, and again in 1960 and 1961. It’s an exact copy of the 2037 locomotive as well as some other locomotives. The only difference is that it lacks magnatraction, but it’s a great runner no matter what. Good luck and happy railroading.