Kitchenaid 600 making a spinning sound, but not actually spinning

Kitchenaid 600 making a spinning sound, but not actually spinning

When I turn the gears on, sometimes nothing happens, but if I turn it up high and jiggle the gear, the engine will make a sound, but nothing that is visible will spin. I’ve taken it apart, but now don’t know what to do! Ha! I’m eager to fix it but I’m a noob.