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 printed on a Replicator 1 in ABS with 0.27 layer height - which may have made the parts slightly oversized and he joints tighter.
You could try imitation's excellent suggestion of using a hairdryer to soften the socket (which the peg goes into) and squeeze it a little with pliers. Or, there's Jorlack's suggestion of drilling holes and threading an elastic band through.
Sorry, I really must get this redesigned in OpenSCAD and Customizer.