single hung window spring
A handy person from Summerfield, Florida says:
July 20, 2016
I'm not sure of the window manufacturer, possible Kinco. Metal channel is 30 inches long, 9/16" wide, 5/8" deep. I think the first two numbers are 86 but could be 96.
Paul from SWISCO responded:
July 22, 2016
Check out our S385-30 channel balance, this looks like it could be a good match.