coil balancer needed

Hello. I have a vinyl replacement window that I purchased from Lowe's in 2005. It is a Reliabilt, Survivor System 7000 (7100) Series double hung window. Atrium now handles Reliabilt for Lowe's. Lowe's suggested your website to me

Anyhow, I am trying to track down a replacement coil balance, either the coil, or the entire assembly. At least that's what I think I need. Attached are 4 photos of the broken coil. The coil snapped on the right side of the sash.

1) I'm wondering if I need to get the entire tandem and coil replacement part

2) do I need to get and replace both left and right so the window tension is equal?

I have all the pertinent window information should you need it as I have kept all the factory stickers that were on the window when I installed them. I would also like to know how to replace this part. The lower tandem has the number 6 printed on it so I'm guessing it's for the 6lb coil

Thank you for your response to my question. Do you have any videos or instructions on how to get the tandem out of the window, and how to replace the coil? I do not have a lower tandem (as some replacement part companies are asking for) nor is there a cutout in the jamb to pull out the tandem. Will it pop out if I pry it from the jamb?