Repairing Double Hung Sash Cords

Reattach the Sash Cord to the Sash Weight. Reseat Pulleys.

ensure your sash cord doesn't split by briefly setting it a light - im using my high intensity cigar lighter - but i bet your father and grandfather used something called a 'match' - a match would likely still work - who knows
and wipe a moist (not wet cloth) over the burning end to fuse all the loose ends of the cash cord together. Do this with both ends of the sash cord and with both left and right sash cords. This where a mixture of natural and artificial fibres for the sash cord helps. The all natural / cotton cord tends to fray quite quickly, the all artificial cord burns a little too dangerously for my taste. The mixed product combines ease of use and historical appropriateness. Also wears quite well.
string the bottom end of the sash cord through the sash weight. have a look at the sash weight you’ll see one side has a channel for the knot and sash cord and other doesn’t.

 

tie a sold knot, actually i used two simple cross over knots but I’ve seen some of these tied with much more elegant  triple knots and figure eights knots which look beautiful but the only people who will ever see them are the next guy who is fixing the window
slide the cleaned up pulley (all the paint is gone!) back into the pulley hole threading the sash cord over top of the pulley wheel

 

i’ve tied a pencil to the sash cord at the top to ensure that the sash cord doesn’t get pulled down back into the sash weight channel. particularly an issue if you have a smooth moving weight – which ideally you should.
a terrible pain to have to rethread this if it got pulled back down at this stage.
put the sash weight back in the sash pocket, put the door back on the pocket, screw the pocket  door back on.