Balance springs replacement
A home owner from USA says:
April 25, 2016
As per your request earlier I have taken pictures of the balance springs that needs to be replaced. I'm not sure if you can clearly see the imprint on the spring, but it says 28B USB on it. Let me know if you have any questions and please send me the link or suggestions which product to buy. Thank you.
Tom from SWISCO responded:
April 27, 2016
Thanks for posting. Sounds like you have a 29" block & tackle balance with a stamp option of 2820. I'm afraid that's all I can tell based on your information, though. Now you just need to pick out the top and bottom fittings in order to determine the Series.
I recommend that you look at our Channel Balance Home Page and follow the steps in order to find the Series that best matches what you have.