You probably can split them, re bearing them, clean the armature and change the carbons but it would take hours, and I wouldn't feel happy unless I've been testing it daily in a machine for a week or so, then you would have to strip the machine again to get the motor out etc.
Put new bearings on a dc07 ydk and cleaned the armature before, that wasn't too tricky but your only one slip/swearword away from having a bad time!