Hi oldbroad, that was at the end of chapter 8 where you have to put the pieces of pipes with the symbols in the right order to make all the lamps in Mechanics burn.
I couldn't match the pattern on the drawing with the lights.
Chapter 17: it is very hard, you have to listen very good to hear how the volume of the tone changes. not the tone changes but only the volume.
Chapter 13: it took me a while to understand it. It should be possible to take the diagram of the wall and look at the diagram from the other side.
In that case it correspond better with the clock wheels in the corridor but you cannot take it of the wall.
Lion_1251
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