The only marking is a patent # 5.737.877 on the plastic in the center of the rod

Question

I have 6 windows that the majority have broken the lower red plastic piece. There is no identifying info on the windows other than a bar code of *77029901.0006$M*

Jasmine · Accepted Answer

Thanks for writing in! Your window balance appear to be an older, discontinued crossbow channel balance. We suggest replacing these with our Series 795 Channel Balance but you'll need to gather a few details to confirm the correct fit for your window.

Take a look at the video tutorial below as a reference for what we'll need to know to identify the correct replacements. You will need to find an undamaged balance to obtain an accurate length.