SWC double hung vinyl




Thanks for posting. This looks like the Series 140 Coil Balance assembly. Look for a stamp, either on this assembly or on the opposite one in the same window, to determine the spring weight you need. If there is no stamp or you're unsure, weigh the window sash; give me that exact weight and I can work out what you need.
Removing these coil balance systems involves extracting them from that 'cutout' in your window track. The video below goes into more detail for a similar coil spring system. Let me know if you have further questions.




Thanks for clarifying. Just to be sure, are the 6 spring and the 7 spring both on the same assembly? If so, that means you have a total support of 13 pounds per side, meaning you have a 26 pound sash.
With that in mind, I'd suggest the S140-13. These are calibrated the same way and can carry sashes weighing 25 through 26.99 pounds. If you have any doubts, you should weigh your sash on a scale just to verify that it falls in that range.