See the threads on improving the smoke unit and you should be able to see copious amounts of smoke belching from the exhausts. I improved mine almost tenfold by disassembling, removing excess "batting" and reassembling with a silicone type sealer. It is sort of a "gee-whiz" addition that adds no function to the tank but it makes it a more visually appearing sight. A lot of people are fooled into thinking it is actually powered by a small tank engine.

I think the design of the smoke generator is quite fine as-is but executing a proper assembly of the thing (on the assembly line in China) is haphazard at best.