Thanks for writing in. Are you sure you have the Series 190? We could use pictures of the pivot shoe and balances, just to make sure we can recommend the right hardware. Many thanks.
OK, so to support your window sash, you are going to need to use coil springs that support 9 lbs of weight individually--if you have two per each side of the sash, that would equal 36 lbs of support, which is close enough to your window sash's weight. We don't currently have 9 lb spring weights for the Series 190 in stock, but fortunately we can get these in for you. Give us time to get these in stock, and we will let you know as soon as they are online. Many thanks!
Good news! The S190-940 9 lb Coil Balance springs are now in-stock! Again, to support your 35 lb window sash, we suggest you use two of these coil springs on either side of your sash, for 36 total lbs of support. Let me know if you have any other questions, and thanks again for reaching out.
