Well, Lauren and I looked all over for it. I put a crowbar under one corner of the tablesaw's mobile base, and lifted it so she could look under the saw. Nothing.
Just as I was about to go turn another one, I got a flash of inspiration... and started looking 'above' the floor.
There it was, tucked very neatly in a small ledge on the back end of the rolling cabinet that the Sand-Flee/Buffer sits on. Lauren said "I would never have thought to look there".
It reaffirms one of the rules I live by: The thing you're looking for is almost always within 18" of the place you think it should be. In this case, it was 6" from the place I first looked, but hidden from view by the cabinet.
Not only can the little sucker roll, it can BOUNCE well.
So, I just spent the last hour drilling tiny tiny tiny holes into the sphere and the rest of the parts, and now I can do the final assembly.
Photos will come after tomorrow's club meeting.