Hey there,
Thanks for writing in! Your coil balance assembly appears to be the Series 140 Quick-Tilt Assembly. Our rep, Steve, confirmed that your sash weighs 35-1/2"lbs. I also see that your assembly is stamped with an 18. Given this information, you'll need the S140-18 Quick-Tilt balance.
This coil balance assembly is compatible with either the 26-398 or 26-405. To confirm which of these pivot bars is the right replacement, carefully compare the dimensions below. So long as at least one of the installation holes match yours, the replacement should work fine for your repairs.
I'm sorry to say that I do not have a phone line I'd be able to speak with you on. This is the only method of correspondence I have to assist you, unfortunately. If it is important for you to speak with a member of our customer service team, they can be reached at (888) 991-1929.
The price of each of these pieces of hardware as well as the shipping costs can be viewed on the website.
