caldwell block and tackle for single hung window

Thanks for posting. I'm confident we can replace this channel balance, but that stamp is not an identifier. It simply tells us the balance's strength. We will need you to remove the balance from the window and show us photos of the nylon attachments at both ends. We will be able to narrow things down from there.

Thanks for getting back to me. This looks like either an S351-29 or S390-29 Channel Balance. The only difference between these two balances is the depth of the bottom nylon shoe, or the 'heel-to-toe' measurement. See the diagram below for reference. Compare both balances with your old hardware to see what matches best. In either case for a stamp option choose 2830.

Comparison of the S351 and S390 balance shoes.

Great! So that would be our S351-29 balance. This would be my top suggestion.

All orders can be placed on our site at your convenience. Please feel free to reach out if you had any other questions. 

Unfortunately, we do not carry a sweep-style seal like yours with the dimensions you've provided. I believe our best options would be something like the 58-135 bubble seal shown below. We can't guarantee that it would work since it is clearly a different style but look it over and see what you think. 

Profile view of 58-135