Customer support for Roomba is quite pleasant. There are detailed troubleshooting suggestions on the webpage, and when that didn't work, the toll-free support line rang through to a real person after one level of phone menu. The first person suggested I used compressed air on a few more spots where debris might be causing a problem.
I'd already determined a need for a run to Home Depot today, to make sure a payment got made on time. While I was there, I picked up Simple Green (in the jug, a quantity not sold at Kroger or Wal-Mart), a timer switch for the fan in our bathroom, and the compressed air.
After that failed to resolve the problem, my second call to customer support netted me a confirmation number for an exchange. All I need send back is the light-est weight removable part, which explains why it has a copy of the serial number on it... Once they receive it, they'll ship me a new Roomba. (She didn't mention whether I'd then return the rest of the old one in the new shipping box, but that makes sense to me.)
So our floors will continue to gather dust while I expend cleaning time in other directions. Three out of four of the bathrooms are clean, and I've still quite a backlog of laundry. Now that Flar's home, I have his two weeks of summer clothes to wash, along with Tigger's 18 cubic feet, and our normal weekly loads.
And I really want to take some time out for crafty stuff tomorrow. Gonna plot supply run tonight during breaks at work...