Tilting Window Doesn't Stay Up

A handy person from Chantilly, VA says:
Found on Window:
Allied Systems Corp
334/4 x 763/4 9-8500
2004-8-20 72934
2862EQ5/8 Flat 9/9; WH49/16cel
Bar code: 12304789.2.1.10

The picture shows the broken plastic housing with a circular insert. In a normal operating window the plastic housing w/ spring attached would be at the bottom of the window not observable(hidden).

What part do I need to repair the window? Any helpful instructions would be appreciated.

User submitted a photo of window hardware.
Profile picture of Tom
Tom from SWISCO responded:
Please see our 15-180 pivot shoe, I think this is a good match. If you also need the coil spring and clip, see our Series 190 and 15-181. You will need the stamp on your existing springs to determine the best coil spring option.
A home owner from Chantilly, VA says:
How does the mechanism work? If I remove the 2 Philips screws will the spring unravel(is it under tension?)? I think the spring is ok but do I have to unravel it to determine the stamp? Any advice on dismantling and reinstalling?

Profile picture of Tom
Tom from SWISCO responded:
The springs shouldn't unravel. At least, not unless they're so totally shot that all tension has been lost. They don't seem to be that bad, based on your picture. The stamp should just be right on the surface. See the video below for more information.
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