These cluster problems are very common. Email a guy named
[email protected]. He rebuilds and modifies clusters, and can get you one fairly cheap. By the way, here is how to get your cluster out:
http://impalahq.naioa.com/ Look under "How To:" and then "How to remove the instrument cluster trim plate"
If you buy a cluster off ebay, be aware that it will not display the correct mileage. Mileage is stored on the cluster itself, and the cluster must be taken apart to reprogram it. Also, just because a cluster will fit in your car does not mean it will work right. Some years and models will only work with certain other years and models.