Help with a block and tackle balance

Hello,

The old style rod-style balances shown in your photos are no longer made. You should be able to use new style balances to replace them but we'll need more information to confirm. First, we'll need to see an intact balance removed from the window, including where the top and bottom attach to the window. We'll also need to know the exact weight of your window sash to determine the spring calibration needed for your replacements. Thank you!