Broken balance spring/coil?

As you can see in the attached photos, we have two broken pieces within the channel of the outer window. We believe these parts are called the balance coil or balance spring but we can use your help in identifying the correct part to order.

The windows are Simonton 6500. Once we are able to identify the part required for repair we would like to place an order. If you also have instructions on how to replace the parts, that would be helpful.