making tracks sag

Run a thin piece of wire or fishing line up through the track and secure both ends to the return roller axle. Cinch it down till you get the desired sag. Run it a little wider than the return rollers so that you get a good looking sag. The track and the rollers hide the wire.

Mike

Another way is to insert pins through the side of the kit at the points where the track sags. The tracks are then placed over the return rollers and under the pins. Paint the pins the same colour as the tracks and no one will ever know they are there.

sound nice, what kind of pins are u talkin about?

Go raid your mother's sewing box. Just plain ordinary straight pins will work. Cut the heads off of them and be sure you are wearing safety glasses when you do it. They shoot through the air pretty fast.