The picture makes this clearer, but basically the drive pulley (where the belt goes) has a splined metal shaft that is press fit into the wooden roller. Apparently there was resistance enough on the roller brush for the splined shaft to shear off the mated wood surface and start spinning like mad, and the friction was starting to burn the wood. This type of failure is usually caused by string, fibers, etc. getting wrapped around the roller and adding a lot of drag. Since we regularly clean off the roller and there wasn't anything on the roller when it failed, I took a closer look. It really seems like there is a design flaw on this particular vacuum, as the splines are actually quite short and closely spaced so they don't make a very solid contact with the wooden roller.
I brought the roller brush to the local dealer (since the roller brush was advertised as having a one year warranty), and they said the warranty doesn't cover that type of failure. I asked what kind of failure is covered, and they couldn't name any. However, they were very willing to sell me a replacement for almost $60.
I declined and headed to my local TechShop to use way more tools than really necessary to re-join the two pieces. Thus the Overkill Edition comment.
I repaired this at TechShop www.techshop.ws
Step 1: Materials and Equipment
Drill bit (size of nail)