Once the line is completely threaded it has to be secured at the end. It is impossible to see this in the photo but essentially, using tweesers, (Imagine you are a surgeon) loop the end of the line under the nearest crossover, pull tight and make a simple knot. I usually apply a drop of ACC to this as I am not the greatest maker of knots in fishing line. The idea is that it should be secure enough to never come loose.
At this point the truss line should already be fairly taught...Even so, the first photo here shows how a wedge of styrene run under the crossover adds a bit of tension. Using a tweezer, pull the line up and onto each of the queenpost castings Take care to be sure the turnbuckles are between the beams. This should take any remaining slack out of the line and make your truss "rods" straight and strong. Center and position the turnbuckles so the open sides are perpendicular with the car side, a tiny spot of ACC on one end of each will keep it in place.
Now is the time to install extra weight. Here I am adding 1 1/4oz. using adheasive backed lead weights from A-Line...It is very important to get this weight centered carefully in the car.