Trying to replace this.

I'm afraid that number alone doesn't tell me what you have. It looks like it could be the stamp from a balance, but that is just an educated guess.

Assuming that I'm right, then it is not enough information to go by. There are 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.