34" long channel, stamped 3350

Thanks for writing in! I've narrowed down your balances to a few possible replacements. However, to identify the exact one, I'll need to see a photo of the spring side of the balance channel. I'm particularly looking to see a photo of the bracket connecting the spring and the string (pulley system) in the middle of the balance.

Take a look at the videos tutorial below for an explanation on removing/installing the balances and other window parts.