"constant force" coil balance assemblies

I need to replace both "constant force" coil balance assemblies on a Gorell 5100 Series double hung window. The window model information is:

PR1178 11/35
NFRC: GOE-K-001-0021

I have not been able to get part numbers from my former installer or anyone else since Gorell is out of business. However, I have watched your excellent "How to replace a window coil balance" video and I suspect the materials used in that video would also work in my window. Question One: How is the coil balance attached to the pivot shoe? Question two: Any other recommendations? THANKS!