I need dimensions for your Series 152 - 7 lb coil balance springs please. I need to buy a coil spring of 1/2 inch wide, max diameter of 1-1/4 inches, and with a length of around 30 inches.
My window sash weighs 14 lbs (on bathroom scale) so I want to buy 2 x 7 lb springs (one on each side). My original window springs broke after 20+ years (as shown in the photos) because I think they originally had the wrong weight springs installed. The window erroneously had 2 x 12 lb balance springs installed (i.e. 24 lbs springs for a 14 lb sash), which I think explains why it was always stubborn and difficult to move. The old coil springs were a double spring set, and always stuck and ended up bending and breaking as we fought to open and close the window. So I want to try 2 x 7 lb coil springs and need to know if yours are the right dimensions please & thank-you!