Once the length of cord is found and cut , insert the two clout nails you are going to use to afix each cord to each side, into the cord at spacings you need!
thread the cord to meet the weight!!! (cue available joke!)..and once the cord is tied to the weight, pull up the cord, until weight is at the top of weight box! then insert an 1½" panel pin through the cord to retain it whilst you carefully nail in the clout nails with the cord being slack.. nice and easy !!!!
and for those who do not know the weight joke... it spans from people trying to be clever and send someone for the obligatory "LONG WAIT!"
well certain peope were more than hacked off when i came back with a 7 pound, sash weight... affectionately know as a LONG WEIGHT!!!!!!!