Out of interest to show the issue, here's a pic of a saddle in the clamp. Look at all the daylight around the rails, and notice how the "support" is concentrated in very thin sections of the rails. That clamp is so tight that I'm afraid I may have stretched the threads on the bolt that holds the clamp together.
Here's the saddle in question...
I too have a replacement clamp on the way, however I fear it is the same clamp with some rough coating on it. We shall see.
Also, it appears to me that this vintage of Selle Italia rails may not work very well with any of these types of clamps, not just Time. The reaason is that the rails are kind of like a diamond shaped profile, versus having flat sides. In addition, the spacing between the rails is a couple of millimteres too narrow, meaing they don't sit in the cups without a lot of force to get them in there before you even start to attach the clamps.
I am now trying a brand new Selle Italia saddle, same profile as the one in the picture, and immediately noticed that the rails have flat sides and the spacing between the rails is wider and fits in the clamp much better. I will report back when I find out how well it holds in riding.