I've long lost the code to this project, by today's standards I'd add some sort of motor-help mode to prevent such issues but can't update it anymore, I'm terribly sorry!
If I remember correctly, there are 3 cog machines you can build, each giving some amount of the currency and stopping after a certain time. There is also an environmental helper somewhere on the map that does the same. Combined it's usually enough to clear the game without much of the manual work around the time those are affordable.