A handy person from Clermont, FL says:
April 9, 2016
not sure on which option to choose for the balance. so far everything looks like it is the 29" series 380 balance (9S380-29). i took the balances out and one had a broken spring (the cause of the problem)the only thing stamped on it is on the top part that says "8A" and printed on the side is either "unique 28-A-10" or "unique 20-A-10". on the top it does have a stamp that says "8A". would it be safe to assume it is a "2810"? just want to make sure before i order these. thank you! see pics
Paul from SWISCO responded:
April 12, 2016
Hello! It's very hard to make out, so I can't tell for sure. I think you're right, the original stamp was probably "28A," which corresponds to our 2810. However, just to be safe, you may want to weigh your sash on a scale and refer to the chart we have on the S380-29 store page.