Spring balance

Hello,

I can't be positive based on your photo but it looks like you may have a crossbow balance as shown in our video below, which has a T-shaped bottom fitting. Unfortunately, these balances are no longer made but you should be able to convert the window to use the S795 channel balances as long as the spring has a diameter of 1/2". Review the video below and let us know if you have any other questions. Thank you!