Really an excellent find. You may want to check the brushes and see if it needs a new set. The brushes are behind the two screws on either side of the head. That's about the only wear part on the thing.

http://www.amazon.com/Motor-brush-spring-Kitchenaid-mixers/dp/B0007WZ6PA

http://www.ereplacementparts.com/article/5787/How_to_Replace_the_Carbon_Brushes_on_a_KitchenAid_Stand_Mixer.html