Channel balance

I am sure we can help, but that stamp doesn't tell us the balance's identity. Only seeing the nylon fittings on both ends of the metal channel can do this. See the video below. 

Hello,

The length of the spring doesn't matter as long as it has the same amount of tension to support the window sash. As long as your sash weighs between 12 and 15 lbs, the 2030 strength option you chose for your replacement balances will work. I'd recommend double-checking the sash weight and comparing it to the chart under our balance product description. 

Also, make sure that the bottom attachment of your original balance measures 1-1/8" deep as shown below. If the sash weight and shoe measurement match the S390-21, the balances you purchased will work just fine. Thank you!