Looking for replacement window balances

We may be able to help, but it's a little difficult to identify what type of balance configuration this is with a broken sample. This style of balance uses a ton of different shoe styles, so in order to move forward I'm going to need to see an undamaged version of that knife lock shoe. Would that be possible? There are many shoe styles that are unavailable to us, so we would need that at minimum to determine if this is a project we can assist with.

I'm also going to need you to weigh the sash panel on a scale and tell me its precise weight, down to the ounce. This will allow us to calculate the proper spring calibration, since your old stamp is a bit irregular for this style.