Which sash stops do I need

Thank you for your patience in this matter while we look into this. Yes, this part is known as a top sash guide. The problem is that I've never seen one like yours before. It's very large and I think it might also be very old, or at least that's what my research so far has suggested.

So I've been trying to look at it this way: a top sash's job is to cradle the balance and prevent it from shooting up in the sash. It doesn't really do much more than that. Plus, yours has a fairly simple design. It's just an upside-down L. This may be wishful thinking on my part, but I'm hoping that this simplicity of design will allow us to use a substitute.

The first thing to come to mind was one of our metal top sash guides, specifically the 18-010. We also have the 18-065, though I fear this may stick out too much. One major detail you'll note is that these don't have that "tooth" sticking down from the bottom of yours. I just can't predict if that will make a huge impact.

Another possibility--and this is a hail mary--is our 18-181. This does have something of a "tooth" and it is more or less shaped like an L, but it's very small.

Look these over and let me know what you think. I cannot guarantee that these will work but they are the best I was able to find. Sorry we couldn't get you anything closer to your original!

Sounds good! If your old top sash guides are still functional then that's definitely the way to go.

If you run into any issues or if you have any other questions, feel free to let me know. We will do our best to help.