Hello,
It looks like your window uses an old-style balance system that is not made anymore. Also, please note that we do not carry replacement jamb liners. Your best bet would be to remove the old spring and try installing our S500 spiral balances and 17-012 mounting brackets. It should work fine as long as you have enough space.
For a wood window, you would determine the balance length by measuring the height of the visible glass and adding 3" for the lower sash and 1" if balances are needed for the upper sash. Take a look and see what you think. Thank you!
