Spirals keep breaking

A professional from Southern New Jersey says:
I put a replacement spiral balance (900 Series) in and it seemed to work fine. It raised properly, but when I closed the window the balance broke.

I tried it a second time and the same thing happened. The 29" balance (metal tube length) is the same as the original. The 3/8" is also the same. I charged the balance four times the first try, and two times on the second try. I watched your video on tilt window spiral balance replacements.

Help, I have ten more of these windows to service!
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Paul from SWISCO responded:
The spiral inside the S900-29 might be too short. Install one, but don't attach it to the shoe or put the sash back in. Instead, see if the spiral touches the sill. If not you can either lower the installation hole or use a S900-30 instead.
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