I'm replacing all 3 of the above and have identified suitable spiral balance replacements (series 600). The pivot bars can't be found on any site I've visited.
They are metal, "L"-shaped with ribs, 2 3/4" horizontal (includes the nub that goes into the cam) w/ 2 screw holes spaced 3/4" apart x 1" vertical w/ 1 screw hole (see pic). Pivot shoe (see pic) is 5/8" thick x 1 1/4" W x approx. 2 1/4" (2 3/16"?) L.
There's an imprint on the shoe of "5900". My sash weighed 26 lbs on my bathroom scale. If I'm replacing both the bars and shoes, is it absolutely necessary to get the same ones I have now or is it more important that the bar and shoe work together and can handle the weight of the sash (and obviously, that they fit in the spaces they need to be installed in)?