Hi Ruth,
I'm happy to help! Our senior expert was able to walk me through the process you would need to go through to replace your existing balances. It will take a bit of work but it is doable. This is a repair that will take two people to complete.
Unfortunately the window balance manufacturer went out of business at the turn of the century. For your metal sash, you will need our S500-29" red tip balances with the 17-012 balance brackets. These brackets hook on the bow tie at the end of the balance spiral.
To install these balances, you would drop them from the top of the sash into the channel. The 33-017 screw is used to attach the balance tube at the top of the window channel. Then you'll need to raise the sash and have someone hold it up while you attach the bottom bracket (17-012) with the 33-073 screw; the U-shape end corrals the spiral.
Next, use your finger to bring up the spiral to the bracket and attach the 75-005 charging tool (for non-tilt windows) and turn the spiral clockwise three turns and hook it to the bracket. Repeat the other side and try the sash. If the sash creeps down, raise and hold up the sash and give the balances another turn or two.
Now the 17-012 doesn't have that extra nylon slide like the old shoe, so you might have to add the 67-002 nylon face guide, two on each side; one on top and one on bottom of the face of the sash. Then slide the lip between the sash and window track and screw it on to the sash. You'll need to do both sides of the sash to keep the sash square to the window track.
Please feel free to reach out to use with any questions you may have!
