No, i've got the same, with the scratches all over it. The one from the first link. It has the scratches in it, but the photo is a bit blurred so you can't see them clearly.
While on the top and bottom the 'secret' is cover by these scratches, the sides don't do a very good job. the problem, at the sides of the block it looks like there is a much deeper scratch which stands out from the rest. And when you notice that on both sides, you can even trace it over the top and bottom of the block.
I also tried cleaning the brass, there was a small layer of some sort of grease on it, but that didn't help.
Oh well, my grandad will visit us today, another victim to test it out.
And on the downside: he used to be a carpenter, so he has a really good eye for small indiferences
So far, out of 5 performances, it has been found out 2 times.
But my sister didn't really look at the brass, because my mother said she already looked at it and found nothing.