Window counter balance

Here is what I have. Any help would be greatly appreciated!!!
I have a window counter balance that has gone bad. It says 34D BSI (I think that is what it says BSI). The roll formed metal is 1/2" x 1/2" x 34" in length. The I have from you is 9/16" x 9/16" x 34" and is much larger. I can send you mine so you can match if needed for a match.
Thank you,

Randi

Hi Tom,

The top is just screwed to the inner part of the window. It looks like a simple tiny "L" Bracket the string is tied to and the other side is longer in length and simply screws to the window casing. Not complex at all.

I am sending back the ones I thought were right I ordered from you. I can send the one we have to you for a sample?

Thanks,

Randi