Since you seem to have a lot of weights Zion, , attach 90# to the string (i use a strong bag filled with dumbells) and hang a tape measure from the handle. Pull up, do it slow so there is NO bounce. If the bag lifts at 24", you're golden. Obviously don't pull it past your draw, just adjust the weights in the bag to get that string back to 24". Not the greatest method, but I don't have a good tillering tree setup and pulling down on the bathroom scale seemed really sketchy to me.