MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
A few things come to mind:
I suggest you wind the mainspring then manually move the balance wheel back and forth. I'm confident that careful observation will elicit the problem. For example, if you give the balance wheel a push, does it start to work and then just peter out?
Good luck, you will get there.