No tilt window block and tackle balance replacement parts and instructions

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Contractor from Methuen, MA

Sep 30, 2025 12:21 pm

I don't know what post means

5 user uploaded images

3 Replies

Contractor from Methuen, MA

Sep 30, 2025 12:24 pm

The number stamped on the metal part of the balance is 2540. On one of the balances there's a space and it says 28 after the 2450. On another one there's a space and it says BS1TH. On another, it says 2540X.

Lauren from SWISCO

Oct 6, 2025 2:44 pm

Hello, thank you for posting,

It appear you have either the Series 351, with a 15-002 bottom attachment, or Series 390, with a 15-001 bottom attachment. Take a look at the image below to determine which balance you'll need.

The length of the metal channel excluding the nylon attachments should measure 26 inches long, please compare.

You mention a 2540 stamp and a 2450 stamp? Was this a typo or are they different on each side? The balance should have the same stamp on both sides. Let me know to move forward. Thank you!

Comparison of the S351 and S390 balance shoes.