Here's a video update about the progress of the LEGOtest machine #2 (#legotest)
Here is some extra info and progress starting with something I forgot to mention in the video: the shorter lever beam.
The lever was too long and, out of sheer luck, one of the shorter beams was the exact length needed. After that, I finally strengthened the base by removing the last LEGO legs and installing the Makeblock leg I showed in the video.
Once that was done it just made sense to attach the Arduino to the front leg as you can see in this picture of the whole machine:
The Makeblock parts are provided by The Little British Robot Company
As for the double action on the new motor; it both assembles the LEGO bricks and helps disassemble them.
The two movements are difficult to perform with a single motor since assembling needs a lot of strength while disassembling is all about subtlety. The part was first designed using LEGO Technics and it took 2-3 iterations before I found a way to achieve the two movements. To better understand the motion, check out the video.