I asked SWMBO to help me vacuum up after some work. I'm not sure how she managed this, but through some mis-application of force, she vigorously pushed my Festool floor nozzle around the concrete garage floor with the roller wheel firmly not rolling. I guess if you don't know how much resistance to expect, you may not notice that it's way too much.
So now I'm ka-thunk-ka-thunk-ka-thunking around. Er...not "round"...