Hello,
We'd be happy to look into this for you but we will need to see detailed photos of both end fittings attached to your balance without anything obstructing it. That will help us narrow down your options. We'll also need to know the exact weight of your window sash since the stamp code shown in your photos is from an outdated system. Thank you!
Thanks for getting back to us. Your balance resembles the S395-24 shown below. We would still need to confirm the exact weight of your window sash that the balances support to determine the corresponding strength option for your replacement balances.
2920 strength options will support a sash between 9-15 lbs. for the S395-24 balances. With that being said, it is important to confirm the exact weight of the sash since the balances will not work if the sash does not fall within the supported weight range.