Thanks for reaching out to us, Sean. I believe you can use the 5/8" diameter Series 500 non-tilt spiral balance with the 17-012 bottom bracket (sold separately). You'll need to obtain the length of the old outer tube to determine the length of the replacements. Regarding the bent metal in your last photo, that looks to be the balance cover but we don't sell replacements for that, unfortunately.
However, below are generic instructions for the Series 500 balance. The 17-012 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 and use a screw to attach the balance tube at the top of the track. Now raise the sash and have someone hold it up while you attach the 17-012 bottom bracket on the sash with the U-shape end corralling the spiral. With your finger, bring up the spiral to the bracket, attach the 75-005 tool, 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.
I'm afraid we don't. Your best bet may be to reach out to the original manufacturer or a local hardware store to see what they suggest. Apologies again that we can't be of more help and best of luck with the repair.
