The Roomba, epsecially the Roomba 400 model that I recently bought, is a pretty nicely oiled machine!! No question. But the batteries do die out from time to time (naturally...)

For those looking for a good spot to replace them (it's inevitable!)--go here: www.batterytex.com

I recently picked up a vac-400nmh-33 for mine. I believe that's the produce number of the battery (not the serial number or anything for the Roomba itself).

-astromantle

I don't see any Roomba batteries on that site.

For up to date info check out www.NewRoombaBattery.com