Replacement Balance
That stamp code just tells us the strength of the spring inside the balance. To know its identity, we will need to see the nylon fittings on either end of the metal channel. From there we will do our very best to help you obtain what you need.
Confirm that the metal channel, not including the nylon fittings on either end, is 27" 28" in length. Does the other nylon fitting, atop the metal channel, have wings, or tabs on its sides (our 19-005)? If so, see either the S380-28 or S385-28. The only difference between these two balances is the depth of the bottom nylon shoe, or the 'heel-to-toe' measurement. The picture below illustrates this difference.
If your top nylon fitting doesn't have wings (our 19-002), see our S350-28.
In either case, you'll then need to choose a stamp option. Your old stamp code of 27-9 is from an older rating system we don't use. To know what stamp option to select, get the exact weight of the window sash. You can then match that exact weight with one of the weight ranges listed alongside each stamp option on the product page.
