The commutator looks to be in good condidtion. (Do not sand it!) Hard to tell about the brushes but they don't appear all that bad, especially to the point where they are not working. If you have a voltmeter or a 12 volt test light, check for power right at the brushes with the battery hooked up and the switch on.
I would almost bet on a broken wire or a bad switch. If there is not power I can give you some more trouble shooting tips. If there is power, then by all means try new brushes.