Chanel balance replacement, Spring broke

Question

I have a Milgard single lift window, non tilt.
The metal channel is 15 in long. Inside channel is 0.5" wide and 9/16" deep. It is marked with the number 1430 with an additional marking next to it with "B.S.I". The windows are old, should I order a set and replace the non-broken one also?
What part number do I order

Tom · Accepted Answer

I can't tell the depth of that bottom shoe. Measure and choose one of the ones below. The 1" shoe belongs to S380-15, and the 1-3/32" shoe belongs to S385-15. Each of those balances is offered with a "1430" option, and you can order online!

Comparison of 15-004 and 15-005