While doing some trackwork on my Ntrak module, I had to remove and replace some track. The track pried up and left the ballast in place nicely, and reinstallation was as simple as pressing the track back into the ballast and respiking.
One area, however, was a little more difficult. The tie strips had come undone from the rail, at a point critical for proper gauge. I found I was able to use any ties from my flex track to place these ties back in the ballast, and then attach the rails with some track spikes and super glue (CA). As a result, I've got my mainline fixed, and a newfound appreciation for my handlaying skills.
What struck me most in this whole process was how easily the track came up from the ballast, and how well it fit back in. After respiking, the track was as good as new.
Puckdropper