Product no needed

I'm not sure what you have, unfortunately. We have dozens of different balances with that stamp. It's not a product code or anything, it just indicates the strength of the spring.

In order to figure out what Series this is, I need you to remove an undamaged version of this balance from the window and show me clear pictures of the top and bottom nylon fittings. I will also need to know the dimensions of these fittings.

All that said, your balance may actually be in good working condition. It seems like only your top sash guide broke. We can help with that, too, but it's the same story: I need to see an undamaged version out of the window. The video below will go into more detail.