CMC 32" Non-Tilt Channel Balance Stamped 31-5 - Replacement

Thanks for your post! You'll need either the S380-32 or the S385-32 to replace your balance. To determine the correct series, you'll need to measure the depth of the bottom shoe.

Comparison of the S378, S380 and S385 balance shoes.

In the title and in the post you mention a 31-5 and 31-6 stamp; however, the balance seems to be marked with a 31-3. These stamps can likely replaced with the 3130, 3150, and 3160. 

It may be a good idea to double check the stamps and sash weights to confirm that they fall between the weight ranges shown on the website. The chart can be found below the product description for the balances.