Where can I get a PD Router Motor?

Having not used my router for a year or so (and it was hardly used at all before), I find it doesn't want to kick into life; after much clicking of the starter switch, it occasionally turns for a split second only to stop and await another session of frantic switch-clicking; I'm told the armature may need replacing. Power is getting to the motor and brushes and all switch gear have been checked and ok'd.