A handy person from Nebraska but window is in Arizona at my vacation home says:
October 27, 2020
Spiral tube seems to be 9/16" with orange? tip (is that red?) 28" in length Pivot shoe measured 1/2" thick (so possibly part 15-015 at 17/32"?)
Casey from SWISCO responded:
October 30, 2020
Hello,
Take a look at our 5/8" diameter S600-28 spiral balance. To identify your pivot shoe, you'll need to remove an undamaged one to confirm the exact width and thickness. Thank you!