Need replacement coil springs, pivot shoe, coil support/tilt assist, and tilt buttons

Hey Andy. The pivot shoe looks like our 15-199, which works with either 1/2" thick Series 160 Coil Balances, or the 3/8" thick Series 165 balances. You'll need to remove your old assembly and compare the thickness of your old coil springs with either option to see which is what you need. You mention the sash weighs exactly 20 pounds. If you have the Series 160 springs, you can just use the S160-10 10 pound springs, one for each side of the sash. This will equal 20 pounds of support overall. If you have the Series 165 springs, you'll need to use a pair of the S165-5 5 pound springs on either side of the sash. This will equal 10 pounds on either side, for a total of 20 pounds overall. Let me know if you have further questions about this. 

For the tilt latches, can you remove an original version and show us pictures of it from a few different angles? That will help narrow down your options. 

Thanks for getting back to me! These tilt latches might be our 26-243 and 26-244; but compare all the dimensions listed in the diagrams below to be safe, including the size of that little clip on the underside.

Alternate view of 26-244

Profile view of 26-244

For the coils, if they are 3/8" wide then you want the Series 165. Now, although your original setup used three coils per side, you don't have to replicate that with the replacements; the number of coils don't really matter; what matters is the amount of the weight the coils can support on each side of the sash is A) symmetrical, and B) supports the overall sash weight. So if the sash weighs 20 pounds exactly, then just using a pair of S165-5 5 pound springs on each side of the sash will get you the support you need. One benefit of this is that it's significantly easier to install a double coil assembly than it is a triple assembly! 

For a new cover, use the 15-150D. The video below shows how to install a similar triple coil system. Let me know if you have further questions.