Help with window balance hardware

Hello, I am looking to find a window balances for these wooden windows that I’m working on. It is by HGP industries And need help identifying.  
I am not sure how to remove the window balance because the inside surrounding the window is plastic and I don’t see a clip to remove it. There are no hinges to the windows that I can fold and pop out and don’t want to force opening it before I damage anything  
Below I attached photos of the bottom of the windows that do have the bottom pin screw inserted in the balance. The other windows do have the balances but the bottom screw pin is missing. I looked on the website and couldnt find it  
To help clarify, these are non-tilt windows and it is a compression sash    

Here are some more images. I was able to open up the jam liner and take pictures of the spring. I will need to order metal clips as well since the other windows are missing it from the bottom.  
Thank you