Stegbar spiral balance part

Hi Guys, just moved house and have Stegbar double hung aluminium windows with spiral balances not working. I can replace the actual balance but need to find the plastic foot that fits to the spiral. These windows are Stegbar D/H Univent and were made 1973-1974.

Stegbar part

thanks for the reply, have contacted Stegbar in Melb. & Sydney and only one person in Sydney can remember these windows but not sure where to access parts for windows this old. Am hoping that a window repairer some where out there has these parts hidden away for me.
There would be engineering works around that could manufacture a couple of these for you if you have the original in the picture. Some would make it out of metal, others work in plastics.
Been to plastics manufacturer, part is too small for them, needs to be plastic and not metal because of aluminiun frames, less noise.
You could knock one up yourself if you are handy. Buy a cheap poly cutting board from the $2 shop and machine as required.