+1 on Zorro's comments. I, as the rider/end user, have succesfully patched & restitched many a tubular & gotten many more miles out of the tire befroe eventually disposing of it. As Zorro says, the trick is to try to locate the leak as well as you can before cutting the tire open, do a neat patch, restitch, & reapplication of the tape & tire. I suspect that this is much like mounting & streaching methods, different folk have different methods.