Hello,
Your coil balance assembly appears to be an older discontinued shoe that is no longer available. The good news is that we have two possible replacements that may work for you.
For this, we typically recommend our 15-192 Certainteed pivot shoe to replace your Simonton brand part but you may need to shave down the aligners from the shoe to install it into the window. Take a look at the dimensions to confirm if it may work for you.
These are compatible with the Series 170 coil balances as well as the Series 171. The S171 is stacked on top of the S170 in situations where there is more than one coil. You would need the S170-407 and the S171-407 (to be used on the double coil). The compatible cover is part 15-156 and the balance drum part 15-157.
The second option is a new assembly that we are also now recommending; the 15-259 pivot shoe. This should fit well in the track, along with the S159 coils springs (you'll need the S159-7) and the 15-256 double support. To use this assembly, the original pivot bars would need to be replaced with our 26-083. We are still in the early stages of confirming if this replacement is a good long-term solution but we have high hopes that it will work with little need for modifications, if any. Take a look and if you decide to give it a try, we'd be eager to hear how it works out for you.
Be sure to carefully review all of the information to confirm which of these assemblies might be the best solution for your window.