Need two Coil Balances Like This
This looks like our 15-087 Pivot Shoe and 15-086 Tandem Housing, as well as the 16-024 Bracket. Please remove your old system and compare the dimensions to confirm. This system uses our Series 180 Coil Balances. Look for stamps on the coil springs to confirm what spring weights you need. If you're uncertain, please give me the exact weight of the window sash, and we'll try and work out what you need.
Well, if the window weighed exactly 20 pounds, you could use a pair of the S180-5 5 pound springs on either side of the sash, which would equal 10 pounds of support on each side, for a total of 20 pounds of support overall. But I highly advise placing the sash on a scale to get the exact weight. If the total weight support you go for is just over a pound above or below the exact sash weight, the window will not function properly. So I highly advise obtaining that exact weight before proceeding.
I understand your consternation. We currently are dealing with hundreds of customers daily, which is why email correspondence is our only feasible option. This is also why we always recommend accurate and precise information up front--in this case the exact weight of the window sash--so that we can save time.
43 pounds makes more sense, since judging from your photos there are at least three coil springs on either side of the sash. In that case, and if the window does weigh exactly 43 pounds (not more), we recommend you use two of the S180-9 9 pound springs and one S180-3 3 pound springs on both sides of the sash. This equals 21 pounds of support on either side of the sash, for a total of 42 pounds of support overall--being within 1 pound of the exact sash weight is sufficient. Again, for the coil shoe and extra tandem housing, see the 15-087 and 15-086. For that top bracket, see the 16-024. Let me know if you have any further questions.