I needed to shift a complete MSTS model down 0.05m for Rail Simulator to get it to sit on the rails properly. As advised, I used this script which seemed perfect. However, later, I spotted that the one object in the root of my model had been shifted upwards 0.05m. I had to put it in a child group, shift it back down and then move it back into the root level again.

Ian

It's a relatively simple script so there's not much to go wrong.
There might be a problem with a sub group if it is not normalised - I'll check.