Spiral balance and pivot shoe difficulties

I have to replace the spiral balance and pivot locks on my single hung tilt windows. Beside these parts, it appears I am missing something from my window itself. There does not appear to be anything on he window that would attach to the pivot lock. Is that a replaceable part? If so, do you have it and how do I insert it into my windows. My windows have been in 14 years and were made by Marquis. I am hopeful it is something I can replace myself without having to purchase a new window.

Here is some additional information that may help. I am at my

I have the same windows/pivot bars and pivot shoes. What I need in addition to the bars and shoes is the spiral b balance that will fit the pivot shoe (15-173) in a 36" 3/8" size.

I have pivot shoes that are an exact match to 15-173. The description of this shoe states it generally works with the 600 series spiral balance. However, my spiral balance measures 3/8" and does not match any on your website. Any help in getting replacement spiral balances would be appreciated.