Identifying window channel balance

Thanks for posting. I am confident we can help, but that stamp does not tell us the identity of the balance, but just its strength range. We will need you to remove the balance and take clear pictures of the fittings on both ends of the metal channel. The combination of fittings used determines the type of balance you have. We should be able to narrow this down from there. 

These are perfect, thanks again. Based on what I see here, you have either our S351-35 or S390-35, depending on the depth of the bottom shoe. That's the only difference between them. I recommend measuring your shoe and referring to our dimensions to confirm the best match.

Comparison of the S351 and S390 balance shoes.