"I have built dozens of Lego sets, including the Mobile Crane MKII #42009, as well as many other Technics sets. This Lego set is the most uniquely engineered, most complex, most interesting design, I have seen to date.
So I was not astonished when Batman presented with one gear that I had somehow failed to include in the Bag #2 build (see the attached photo).
No worries though. This is Lego. Just take it all apart and build it again. So that is what I am about to do.
If you are looking for a challenge and an opportunity to build a truly well engineered, incredibly well designed mechanical device - then build the Rough Terrain Crane."