Balance Springs

Hey Scott. Good questions. I'll take each one at a time: 

• The shoe on your balances is either the 15-004 or 15-005. The difference lies in their depth, or the measurement from 'heel-to-toe'. See the diagram below for reference. Long story short, if it's greater than 1", then the shoe is the 15-004, and therefore you'd need Series 385 Channel Balances. If it's 1", you'll need the Series 380.
  

  Comparison of the S380 and S385 balance shoes.
• The first two digits on the stamp codes actually refer to the height of visible glass in the window sash. The metal channel length is usually 1" longer than this. Hence why a balance stamped 33-5, for instance, is 34" long. 
• The third (or sometimes, third and fourth) digit is indeed the stamp code. So, for a balance stamped 33-5, you'd choose our stamp option of 3350 for a replacement balance. These are equivalent. 

You also have balances stamped 33-9. You will note that we don't have any stamps that end with a -9 or -90. This is because these designations are from a rating system no longer in use. To know what stamp option to select in this case, weigh the window sash the balances support. You can then match that exact weight with one of the weight ranges listed alongside each stamp option under the product description of either the S380-34 or S385-34 shop page. 

Let me know if that all makes sense, or if you have any other questions! 

Glad to help, Scott. Let us know how you make out, or if you need anything else.