Window channel balance

Thanks for your photos. Based on what I see here, you have either our S351-25 or S390-25, depending on the depth of the bottom shoe. That's the only difference between them. I recommend measuring your shoe and referring to our dimensions to confirm the best match.

That's definitely a problem. If the 2420 and 2320 are in the same window, then that means someone put in the wrong replacement part at some point in the past, likely while doing a repair.

Fortunately, it's something we can still figure it out. What I need you to do is measure the height of the visible glass. Note that I don't need the size of the entire sash, just the visible glass. I will also need the precise weight of the sash, down to the ounce. That will allow me to calculate the proper length and weight rating.