Photos: The insides of a Roomba

After separating the dirt bin and removing the filter, you can release the brush guards that hold the two brushes by pressing two yellow tabs. The main brush has one square side (large) that plugs into a socket on the underside. The flexible brush has one square side (small) that plugs into a socket on the underside.

This is the underside of the Roomba with the brushes removed. Here you can clearly see the dirt detect sensor (the gold sensor on the right side). This sensor detects areas of the carpet that need a little extra vacuuming. It detects this state and circles around the area, gathering the excess dirt.

Credit: CNET Networks