non-tilt window channel balance

Thanks for posting. I am confident we can help, but that stamp just tells us the strength of the balance. To know its identity, please remove it from the window and show us clear photos of the attachments on both ends. The style of attachments determines the balance you have. We should be able to help from there. 

Thanks for getting back to me. This looks like either an S380-33 or S385-33. The only difference between these two balances is the depth of the bottom nylon shoe, or the 'heel-to-toe' measurement. See the picture below to get an idea of what I mean. Compare both balances with your old hardware to see what matches best.

Comparison of the S380 and S385 balance shoes.

You then have to choose a stamp option, which as I said, denotes the strength of the balance. Your old balance's stamp of 3290 is actually from an obsolete rating system. To know what stamp option to select for the replacement balances, weigh the window sash. You can then match that exact weight with one of the weight ranges listed alongside each stamp option under the product description of either the S380-33 or S385-33 shop page.