Broken black channel balance blocker

Oh and by the way, I asked someone from your Help department for this one and he recommended I add this to my discussion.

How can we maximize the longevity of our channel balances? We have had to replace the channel balances in several of our windows--averaging about once a year. The string is what always breaks and usually only on one side. After I change out the balances (I usually switch out both sides if one breaks), the window works smoothly for several months to about 1/2 a year. 

Then gradually it seems like the tension starts to build and the windows start to require a bit more force to close. Usually shimming it up and down seems to help, and occasionally I'll take the windows out to inspect no dust or things have gotten caught. They usually look fine and work well for a few more months after doing this. Sometimes I'll add some wd-40 to the spring, but that doesn't seem to make any difference.

Unfortunately, I don't have the original balances for one of the windows as I replaced them back in 2017. I was able to find some photos from back then when I first found Swisco, and you guys help me get new parts. Images 1-6 are of those balances from 2017. I believe this window is about 10lbs. This window's balance's strings broke again in 2022 and again a couple months ago. Each time, it has been the strings that fail. There is a second window that weighs about 20lbs. I replaced those sashes back in 2022. Photos are IMG_2251 and 2252. I realize these sashes may be over-weighted now for the 20lbs window. Could this be why this particular window is hard to close? Any help with figuring out what I may be doing wrong would be greatly appreciated.