Simonton Spring parts
Hey there, thanks for reaching out to us. We can definitely supply the pieces for t his coil balance assembly. To start with, it looks like you have our 15-199 pivot shoe. However, this is compatible with two different size springs: the 1/2" thick Series 160 and the 3/8" thick Series 165. You'll have to measure the thickness of your original spring to confirm the best match. You'll also need the stamp on the old spring to determine the best strength option.
Finally, it also looks like you'll need a new cover. The Series 160 uses the 15-150D double support, while the Series 165 uses the 15-204 double support.
The video below may also be of some help to you.
Perfect! I agree, the Series 165 would definitely be the spring you want. Concerning sash weight, I think you would be okay with the 5 pound option, S165-5. It seems the installers of your old springs agreed with me, since they have the same calibration. Four 5 pound springs can hold up a 20 pound sash. That extra half a pound shouldn't make a difference.
Your pivot bars seem to be in good condition so I don't think you need to worry about replacing them.
Unfortunately, we do not. A local glass shop should be able to help you out if you bring them the sash in question.