Need to know the Caldwell channel balancer model number

That stamp code indicates the strength of the balance, but not the kind you need. Please show us pictures of the nylon fittings on either end of the balance. From there we should be able to narrow this down.

Thanks for getting back to me. Looks like you have either an S380-27 or S385-27. The only difference between these two balances is the depth of the bottom nylon shoe, or the 'heel-to-toe' measurement, so compare both with your old hardware to see what matches best. You'll have to choose a stamp option. Your stamp code of 26-9 is from an older rating system we don't use. Obtain the exact weight of your window sash. On each balance shop page there's a chart that shows the corresponding weight range to each stamp option; you can match your sash's exact weight with one of those weight ranges.