Replacement window balances

A contractor from Gloucester MA says:
We have a number of broken springs supporting windows that went into the unit around 1980. They are single glazed windows and we do not know the manufacturer. If you can match these spring mechanism from this picture or if you have a better approach let us know. The springs fits into a 3/8" wide channel and we would need 4 at 37 1/2" and 4 at 49 1/2" long measuring from the very top of frame to where it hits the sill.

See attached three pictures showing the top, the bottom, and one of the whole springs with the bottom broken off. The length of the spring is 15" and including the top it is 16 1/2" long. This is the length for the longer of the tracks we sent the measurements for yesterday. The diameter of the balance is 3/8 of an inch.

User submitted pictures of window balances.
Profile picture of Paul
Paul from SWISCO responded:
Thanks for posting, Andy. For the 37-1/2", please take a look at our S400-20; for the 49-1/2", please take a look at our S400-25. Also take a look at our 17-031 metal bracket. Do you think these might work for you?
Reply to Thread
Use this form to ask a follow-up question or to share your experience regarding this subject.
(your email address will be kept private and is only used to inform you when a response has been made)
Current wait time is 4-7 business days
We promise that one of our experts will personally get back to you as soon as they are able. Thank you very much for your patience and understanding. If your inquiry is time-sensitive, please feel free to reach us at 856-317-6263 or at