Need Caldwell Block and Tackle Balances

A handy person from Dunedin, FL says:
My approx. 44"x 60" window, single hung , vertical slide, tilt-to-clean window: the block and tackle balance came unstrung on one side(broken string). I removed the other side which still looks quite serviceable. Shoes still look good. It is a Caldwell 26 9 K04S CMC.

Also, I know the balances are probably fifteen years old. Should I go ahead and replace both balances?
Thumbnail of the uploaded file named IMG_20201128_161514336_HDR.jpg
Thumbnail of the uploaded file named IMG_20201128_161608387_HDR.jpg
Thumbnail of the uploaded file named IMG_20201128_161617911.jpg
Thumbnail of the uploaded file named IMG_20201128_161649602.jpg
Profile picture of Casey
Casey from SWISCO responded:

Hello,

Your balance resembles our S765-27 channel balance. The stamp indicates that you may need a 26-9 strength option but you can also weigh your window sash to confirm that it falls between the 30 to 34 lbs range supported by the 26-9 option.  

We always recommend replacing both balances at once, especially considering the age of yours. Thank you!

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.