Broken cam in balance spring shoe

I have a window from CertainTeed manufactured in March 2006, series 8500 36x72". The label is attached. The plastic cam in the pivot shoe is broken so the shoe will not lock in place when the window is tilted. The spring has snapped up into the top of the channel and the window will not stay open. We are selling the house and this was noted in the inspection, so I need to repair it prior to settlement. CertainTeed no longer carries this part and suggested that I contact you.
Thanks