Simonton 6500-Series window balances

Greetings. Three of our Simonton 6500-Series vinyl windows, purchased by former owner in 2010, have broken or missing constant-force spring parts. Two of them use double springs, which are working, but the plastic sliders that push against the track to hold the window are broken or missing. One is a smaller window with broken slider. Your video appears to indicate that you have replacement parts for this kind of mechanism. What do you advise? Thank you.