Searching for northeast vinyl window ballast
Thanks for writing in! It appears that you have a window pivot shoe that is made specifically to interact with spiral balances, not coil balances. It also looks like you have the 15-086 Tandem Coil Housing installed in the window as well. Given this information and based on what I can see, it looks like you likely need the 15-087 Coil Pivot Housing.
These are compatible with the Series 180 Coil Balance Springs. To confirm the correct spring strength for your coils, I'll need to know the exact weight of the sash, down to the ounce.
You may also need the 16-024 Mounting Bracket.
Please let me know if you have any questions.