Need window balance replacements

I'm afraid your balance is too damaged to identify. Some very important details are missing from your photos.

The best place to start is taking an undamaged version of this balance out of the window and show us a photo of the top and bottom ends. It's vital that we see whatever shoe, clip, or hook is at either end; basically all relevant attachments. It's not possible to identify otherwise, so this isn't a step we can skip. If you can't provide that information exactly as requested, we can't move forward.

Once I have a better idea of the balance, I should have a good idea of what pivot bar will work best, as well.

Thank you for providing this additional information, that is a huge help. Your setup is new to me; I've never seen the clip you show in your second photo before. Otherwise your balance appears similar in design to our Series 795, just calibrated for a very, very heavy sash.

This is a weird one. Please give us a little more time to see if this is something we can offer and we'll get back to you ASAP.

Okay, we've dug up some additional information on this balance. I see the original  stamp was 36JU, which is for a channel that measures 36". Additionally, it's calibrated for an upper sash weighing 45 through 48 lbs.

For a sash balance like yours, the strongest spring available for 36" is the 36LU (upper) or 36LL (lower), each of which being calibrated to hold 51 through 54 lbs. These should be sufficient for your sash weight, but it is curious that your weight differs from the stamp you already have.

Did you ever find that the window was hard to open in the past? If not, you may want to triple check the weight just to be 100% sure. Otherwise, let me know which stamps you'd like quoted and we can work from there.