Need new part - window will not stay open

A quick learner from Jacksonville says:
I need to replace two of these as my window will no longer stay open. The window is very heavy!

The width of these are 1/2 inch and they are 30' long.
User submitted photos of a window balance.
Profile picture of Tom
Tom from SWISCO responded:
Hey, thanks for posting. I've narrowed this down to two possible channel balance Series: either our Series 380 or our Series 385 balances.

Now, as you can see, there is only one difference between these two Series, and that is their bottom shoe. The Series 380 uses the 15-005 while the Series 385 uses the 15-004. I can't quite tell what you have based on your pictures, though. Please carefully compare their dimensions to your own hardware and see which is a better match.
15-004 and 15-005

We also do not have an option that corresponds to your stamp of 29-9. I would like to know the exact weight of your window sash so that we can determine what would work best with this balance.
A quick learner says:
Window weighs 33 pounds
Profile picture of Tom
Tom from SWISCO responded:
Great. Assuming your metal channel is 30" long, I recommend the 2960 option regardless of which Series you choose.
Reply to Thread
Use this form to ask a follow-up question or to share your experience regarding this subject.
(your email address will be kept private and is only used to inform you when a response has been made)