Anyhow, my newly refurbished window is working very nicely at a pound over & under - with sashes that are around 15 lbs each. The sashes didn't move at all, even when the sash was hanging loose before the beading went in - the friction of bending the cords round the pulleys was enough to make them stay put. The brush seals in the beads are now of course adding more friction to hold them in place.
