What replacement parts do I need for these Milgard windows?

[solidcell]

They're from around 1999. Unfortunately any labels that were along the track were either removed or have deteriorated away. Any help finding which replacement part I need to replace this would be very much appreciated!

[Windows on Washington]

You can call them if you like, but you'd probably be better sourcing it 3rd party. Milgard didn't make that balance, just used it in the operation of their window.

It's call a "Side-Load" balance spring.

There should be a number or stamping on it that will indicate it's size and they can be ordered from suppliers like Blaine Hardware.

https://youtu.be/-TAjm4X8ubI?feature=shared