Nice machine! I'm partial to National's. The plated swing away motor that you speak of, is often labeled Hamilton Beach, but you would need the entire swing away pivot arm with it's spring.
[ATTACH=CONFIG]475418[/ATTACH]
You may be more able to find one of these motors[ATTACH=CONFIG]475417[/ATTACH] this picture is the before it got rewired... perhaps you could post a picture of the backside where the motor would mount??