I have an American Craftsman Series 8500, double hung, installed in 2005.
It appears that the lower sash coil spring got damaged and doesn't function.
I have not yet taken the Pivot Shoe and Coil Spring out to get exact measurements, but it appears to be very similar to your Coil Housing Pivot 15-087 except, as near as I can determine, the depth of mine is 9/16", not the 1/2" shown on the 15-087 detail (I see that the depth of the 15-086 is 9/16").
The sash is small, only approximately 18" by 20", and I weighed it as 5.75 pounds.
I can find no marking on the end of the coil spring BUT I do see the number 4 marked on the Coil Housing! So perhaps they use a 4 pound coil to assist. So I plan on ordering the "Coil Housing Pivot 15-087 and the Swisco Series 180 Coil Balance with a 4 pound spring weight.
Would you also suggest that I replace both left and right sides?
Can you confirm that I am on the right track before I order the parts?
Thank You
Lenny
Pictures:
Three pictures included 0891,0896 and 0905
Two pictures show parts of the damaged coil spring, the third shows the dimensions of my Pivot Shoe.