A home owner from Wibter Haven Florida says:
June 22, 2016
I have a 35" channel sash (3/4" x 5/8") that needs replaced. It comes from a single hung window that is 16 years old. it has a spring down the center of the channel wit a string and pulley system. Do you have a replacement that may work.
Tom from SWISCO responded:
June 23, 2016
Thank you for the pictures, it looks like it could be either the series 380 or series 385. Check these out and see if they work for you.