I have several windows with these spring units, I was hoping to identify a replacement as most have at least one broken string. Each spring has the ID "F3 12 31 1 171" stamped on it, though the 12 31 part in the middle is bigger. Do you have a replacement spring unit for these?
Thank you.
Dan
A home owner from Michigan says:
July 15, 2014
One more file, this time with dimensions. 2 7/8" x 6 1/4".