I am not sure of the window manufacturer. It would have been assembled sometime around 1999 as that is the time my house was built. I have several windows that need the balances replaced but I am going to start with one of the smaller windows to make sure I can do it.
I am not certain how to remove the balances as the tops run all the the way up the window frame from what I can see. I am attaching photos and the outside identifications are 18R BSI GL. From your website the locking terminal appears to be a Great Lakes unit but it is a white color.
I don't see a way to remove the balance as the channel appears to run the entire height of the window frame.
Thanks
Brent