identify my spring balancer 3640 BSI vo

Hello, thank you for posting,

It sounds like you are in need of a new channel balance. Unfortunately we cannot confirm the series from the stamped number alone. To further review, we will need to see the balance removed from the window where we can see clear images of the top and bottom nylon attachments. From there we can narrow down the correct replacement for your window. Thank you! 

Hi Sanjay,

Your balance uses the 19-038 top and 15-193 bottom shoe fitting. This configuration will require a custom order to assemble for you. 

The length of the metal channel excluding the nylon attachments should measure 37" long, please compare.

I have sent over an order link for (2) balances with pricing for your review. If you need a different quantity, please let me know but there is a minimum of (2) for custom orders. 

Let us know if you have any additional questions and custom orders are nonrefundable. Thank you!