Coil Balance Replacement

The plastic cases on the coil balances shown in the photos are cracking and falling apart. Recently I purchased a pair of your coil balances p/n S140-11 to try in one of the failed, single sash windows. I was able to get them to work, but had to install the coil assembly further down in the track toward the window stool in order to get the window to close.

I also had to remove both the front and back edges of the track at the top in order to get the old one out and new one in. I could not justify purchasing your frame expander set. This created a gap at the top of the window that prevented the window from being raised all the way without the window top potentially falling out of the track. I remedied this by drilling a hole on each side of the window in the track and inserted a screw to prevent the window from being raised all the way up and into the opening.The existing balance has two springs attached in series, end to end. I believe each coil is 5 lbs. I was unsure if that was the equivalent of a 10 lb. coil or just a long 5 lb. coil, so I ordered a pair of the 11 pound balances just to make sure there was enough force to lift the window. The window operates smoothly now.I would like to know if I can use the smaller 10 lb. balance (or 5 lb.?). Since it's smaller it may allow the coil to be installed in the original position in the track without interfering with the window closing. In addition, maybe I can cut a smaller opening at the top of the track than was done with my test window.The info on each of the two coil stamps reads " #5.0 35" on the first line and "?AT5232??? where I can't read the characters represented by question marks.Thanks,Joe