Spiral Balance and Pivot Lock Shoe on single hung window

A quick learner from USA says:
My photo titles: 38 inch means 3/8"; 58 inch means 5/8".

I have old windows made in 1980. I bought this place just days back and got installed new spirals but could not find Pivot Lock Shoes. My contractor worked on that for me.

Now the windows are great but they dont stay up. My contractor says that its because of the Pivot Lock shoes and he could not find that anywhere. He suggests to put a wook block between the frame each time I open window to keep it open for fresh air. The windows with new glass in them is heavy and I cannot have this arrangement as this is very risky and could prove fatal.

Window specifications:
Old Spirals: 22 inch long, 3/8 inch wide and Red color tips
Window sash with glass weight: 20 pounds
Pivot lock shoe pic: attached
New Spiral pic: Attached (the new spirals are 22 in, 5/8 wide and
User submitted photos of a window balance.
Profile picture of Paul
Paul from SWISCO responded:
Hello! My first thought when I see the photos of your window was that they might be Acorn, but Acorn used odd length balances. Also, the white top tilt latch isn't original, so I can't be sure. What I can tell you is that you have the old style pivot shoe that has since been replaced with the 15-015. I would also recommend the 26-040 tilt bar. Carefully look our information over for these parts to confirm. For your window balances, I suggest the S600-22 blue tip for the 5/8" diameter balance, and our S900-22 blue tip for the 3/8".
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