I've removed the lower sash from my window. House was built in 1860's (upper Michigan), renovated in 1900 and 1940. My best guess is the window was from the 40's. The lower sash has a coil balance x 2 at the top of the jamb on each side. Coil was busted on one side and other was intact. The coils were attached to what appear to be flat copper that was wrapped around the outer portion of the coil and then exits the jamb and attached to the sash after running in a channel along the side. I need to replace one of the coils and am having trouble figuring out which one to get and where to even find it. Best plan I've come up with was to weigh the window, divide by 2 and buy a coil for that weight and re-assemble the balance system. Any help/direction is greatly appreciated!