Alliance Vinyl Replacement window parts

A handy person from Brooklyn, NY says:
October 15, 2017
I had 8 double-hung replacement windows made by Alliance (I was told they were a division of Certain-Teed) installed by people from Doody's Home Center in Brooklyn, NY around 1999. I have a problem with most of the windows, I believe related to the balance springs, as some of them are difficult to open without a lot of force, and some won't stay open (they come slamming straight down). I need to replace the vent locks on most of them as well.

I have included pictures of the vent locks; they measure 1 5/8" (L) x 3/8" (W).

As far as the spring replacement is concerned, do I purchase the individual springs (which I suppose I then need to load in to the cassette), or am I able to purchase the entire cassette? I have included pictures of the broken window and the last picture (picture 7966) is of the jamb of one of the windows that works normally.
User submitted photos of window hardware.
User submitted photos of a window lock.
User submitted photos of window hardware.
Profile picture of Tom
Tom from SWISCO responded:
October 20, 2017
Thanks for posting! Your pivot shoe looks like our 15-175, which is most commonly used with our Series 152 coil spring. You can purchase the springs by themselves, yes. As long as everything else is working properly they can be reused.

As for the vent lock, see our 26-362. I'm not sure about the window lock itself. Can you tell me its hole spacing, center-to-center?
A quick learner says:
October 20, 2017
OK; thanks. I will order the parts.

I don't need a new window lock - I just sent the picture to help in identifying the window.
Sash Vent Latch
Sash Vent Latch
26-362
$2.12
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