Anderson Window balance

A home owner from Pittsburgh says:
September 3, 2017
Purchased three sets of balances from you in 2015 and two of them do not hold up the lower sash. Can you tell me if the replacements were the correct ones. The original window balance is the Anderson 11600-17 model. The Swisco replacement I was sold was 737 1/15 and they are not holding up the lower sash.

Please advise
Dave
User submitted photos of a window balance.
Profile picture of Paul
Paul from SWISCO responded:
September 8, 2017
Ah, the markings can be kind of confusing. The "11600" number doesn't mean anything in regard to choosing a replacement balance. It's the other code that does all the talking.

If the balance in your bottom left picture is the original, then we recommend our 24-R12-827. Keep in mind this is a right-handed balance, so you'll also need the 24-L8-1227, which is the left-handed version.
Andersen Sash Balance, 725, 727, 731, 737
Andersen Sash Balance, 725, 727, 731, 737
24-737
$54.20
Andersen Sash Balance, R12 827
Andersen Sash Balance, R12 827
24-R12-827
$54.20
Andersen Sash Balance, L8 1227
Andersen Sash Balance, L8 1227
24-L8-1227
$54.20
How to replace an Andersen Window Balance
How to replace an Andersen Window Balance
VIDEO
WATCH >
Andersen's Narroline Sash Balances
Andersen's Narroline Sash Balances
GUIDE
READ >
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)
Current wait time is 3-4 business days
We promise that one of our experts will personally get back to you as soon as they are able. Thank you very much for your patience and understanding. If your inquiry is time-sensitive, please feel free to reach us at (888) 991-1929 or at help@swisco.com.