The height of the teeth on a rotor bar should be approx. the same measurement as the thickness of a lead pencil. The leading side of the teeth should be square. If the teeth are rounded over and sloped from the leading edge to the rear edge, the bars should be replaced. When replacing, be sure to clean out dirt, etc. from under the mounts as well as you can so you can check balance properly. Weights of most replacement sets are fairly consistent, but it doesn't hurt to check weights with a scale and write them on the bars. You'll observe that you actually have 4 rows of bars. Try to add up the weights of the bars so you'll know the weights of each row and install rows which are matching in weight in opposite each other. Hope this is reasonably clear.