Once you put the tracks in the water, let them sit for a little bit, then carefully stretch them. You do need to be careful as not to pull them apart. It will take a couple, maybe even more trys doing this, but it does work. OR like Shermanfreak said, you'd probably be better off now getting after market tracks.
they can be easily made to look loose as they are individual links. Some are even metal and the weight themselves give the saggy look you need for your tracks. They really are worth the money. HTH'd Chris.