To replace the balances, first tilt in and remove both the top and bottom sashes. You would then place a flat head screwdriver in the metal cam of the pivot shoe and turn it to unlock it. This will allw you to slowly bring it up to the balance. Make sure to do this gently, but firmly. If you just let go of the screwdriver, the shoe will shoot up the jamb track!
Now, the jamb liners are held in by the pressure of the sashes, so you should be able to just pull them out of the wood frame. Unhook the balance at the top and slide it out with the shoe attached. You can reuse your old S-clip and pivot shoe if you want and install them to the new balance. Slide the new balance in until the S-clip hooks on the jamb liner where it went originally, put the jamb liner back in the window, and finally use your screwdriver to bring the shoe down low enough that you can put the sash back in.
Thanks for the detailed instructions on handling the jamb liners.
Any thoughts about a replacement for the broken balance?
Thanks,
John