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.
You free the outer sphere not by running a knife around the groove, but by sticking a small screwdriver blade in the gap and then prying inward gently. Do this around the whole perimeter. Check out the video posted by NeatherBot: https://youtu.be/L5bD2DMX8BE -- it shows really nicely how to get it freed up.