Spiral balance tubes

Hi, my tilt windows in my sunroom were installed when the room was added in 1999.
I didn't move in until 2016, and they have never opened/closedd easily.  Some make a hideous, loud clicking noise when opening.  I think I've determined that it is likely my spiral balancing tubes.  I've determined that it is a 3/8" tube, 29" long, but there is no color on the tip.  I've weighed one sash as 18.4 lbs.    I'm only going to order 2 at this time to be sure they are the right part, and then I will order the rest.  I plan to sell the house this time next year and will not be replacing the windows.  But I, at least, will hand them off to the next buyer in a much better condition than they were handed to me.  I would also like to know which spiral charging tool I should get.