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.
I have a couple of recommendations. Try printing the center pin with more infill to make it stronger. Also, it is very important to make sure that the cube spins freely. Please see the pdf instructions for suggestions on lubing and breaking in the parts.
If it cannot spin freely, I recommend checking the calibration of your printer using one or more of the many calibration prints on thingiverse. I used to have issues with my X axis being longer than my Y axis which led to my printer making gears that were not round. They would not turn for me because they would bind.