How did the machine get Awakened in the first place? It seems like the yoki-hijo were the only humans that showed any signs of Investiture, and we have seen that Awakening metal objects takes a lot of Breathes and therefore a lot of Investiture.
The small machine was able to be kick-started by a single spirit, but it seems like that wouldn't nearly be enough to match the 1000 Breathes, or however many, that it takes to Awaken a non-human object like that. Especially since that even happened 1700 years ago so probably even before the contemporary novels.
Or maybe I just missed something