Jeld-wen double hung window replacement part

Hi. I need help identifying this part in the photos. They continue to break when I take the windows out, and it helps with lifting the widow. Without it, the window doesn't stay up by itself. Do you know the name of the part and how it's sold/price/etc? I think it's called a friction shoe, and I'd like about 10. Please let me know if you need further information on the specific window in the photos.

Thank you that should do it!