Window Balance 34C HC3 CMC1

Hello, I have a broken balance spring on a large window. I've included 2 photos of the broken part and 1 photo of the part on the side that is not broken. There is some writing on the broken part: "34C HC3 CMC1". The window itself says "Duraseal L22 091107 22:45".

Any help determining the correct replacement part would be much appreciated.

Thanks!