Block and tackle balacer
Hello! Looks like you have an old rod type balance, or "crossbow" balance as they're called in the trade. This is a very old model that is unfortunately not made anymore, but the good news is that we have a modern replacement that can be used as an alternative.
Before we go any further, I highly recommend that you measure the diameter of the spring. If it's 1/2", then you can use our Series 795 channel balance as a replacement. The process is a little involved but we have a handy guide that will walk you through it every step of the way. Watching that should be your second step after measuring.
If your spring is 3/8", instead of 1/2", then our Series 795 won't work. Let me know if that's the case and we can look into alternative solutions for you.