Vinyl window sash balance

I don't have any numbers. I read that this part has been discontinued but there are things that will work in its place. It is 27" long. I need one for each side. The top sash is working properly, this is for the bottom. As you can see in one of the pictures, the top part of the window channel it goes in, the balance clipped in vs. screwing in. The clip broke while trying to get it out. What replacement part do you suggest? Thanks for your help!