Replace coil balance

Question

I'm trying to replace the coil balance in the attached photos. No markings, names or numbers that I can see. The one on the left is broken (pictures are from the unbroken one on the right side of the window). I suspect these are original to the windows (20+ years old). The window weighs ~15.4 lbs.
I would like to find 4 of these so I can replace both on this window as well as two on a windows to the side of it.

Bob · Accepted Answer

Hello there. This looks like a 15-180 Pivot Shoe, which works with Series 190 Coil Balance springs sold separately. For new housing, see the 15-186 and 15-182 Drum. If a sash weighs 15.4 pounds, you can use the S190-840 8 pound springs, one for each side of the sash. This will give you 16 pounds of support total (being within 1 pound of the exact sash weight works just fine). Let me know if you have questions.