Why not corporations? They would be owned by the market and compete against each other to offer best quality machinery.
Of course you still have the leadership class of people that could be corrupt, but that can be solved e.g. by sortition https://en.wikipedia.org/wiki/Sortition
+ you need anti-monopoly laws and some solutions preventing competition-to-the-bottom (e.g. if marginal cost of service becomes 0, it may no longer make sense to compete for it, so it needs to enter some sort of maintenance mode to keep quality in check)