A few questions
1 Is this just the impeller. or both the impeller and auger?
2 Does the impeller and auger turn with no load?
3 Can you turn the Auger by hand?
It sounds like the roll pins that hold your impeller to it's shaft have broken. You can usually access them the the hole where the chute is. Remove the chute and pound new roll pins threw where the old ones were. A large punch helps with this.
Here is a breakdown to help you better understand. The part I am referring to is #341.