[m463]

They don't seem to say why it didn't work.

I wonder if it was not just the change in gauge, but tolerances as well.

I got to see "Dr. Yellow" running on the shinkansen line and it checks everything out.

https://en.wikipedia.org/wiki/Doctor_Yellow

I wonder if the slower-speed lines have looser tolerances.

Then maybe running the gauge-change train on the slower lines might kill the train's tolerances before it moves back to the super smooth high-speed lines.