Hi Angus, I am not a Brawa collector & therefore am not familiar with that loco at all. I am sure other members of this forum might be able to shed some light on this. But I am assuming that the shell / body of the loco is metal. If that be the case you need to check which colour wire on that loco corresponds with earth & take that wire & lets "assume" it is brown & connect it to the chassis where the other corresponding earth is or anywhere that is suitable. Assuming that the white wire is the power wire for the smoker, connect that to the base of the smoker. The body of the smoker will act as the earth when inserted through the hole in the body & it is normally a tight fit. Alternatively you could solder on the side of the tube the earth wire once inserted into the body. But before you do this make sure which wire is which. Use a test lamp to establish namely that the two wires are what you think they are & then sort the +ve from the - ve. My two cents worth from a former Jo-Burger.

U is welkom meneer: Any chance of a better close up picture of the Smoke unit base? What Bike is that in your Avatar? I have a BMWG650GS

Problem solved.

The white wire goes on bottom of the smoker and the brown wire goes onto the body of the smoker. Should've guessed the brown would be ground.

Now looking good puffing away with the Messerschmitt consist behind