Balance replacement for large Pella double-hung window

Hello,

Your balance resembles the S751-38 (37TG) at first glance but I can't be sure with the assembly still installed. Take a look and compare the specifications below to yours, as well as confirm the length of the metal channel. Also, note that our balances come with ribbed channels, which is tough to determine while it's inside the jamb liner. If you notice any discrepancies, please get back to us with photos of your balance and fitting uninstalled. Thank you! 

How to measure the length of the Series 751 channel balance.

Dimensions for 15-014