The cable that you are referring to is called a cable spool. This allows communications between the picker and the main board. The trick to separating the units is to open both doors and manually move the picker into the top unit. In fact, there is a small metal tab just inside the door of the top unit (on the left) that will pivot out to hold the picker in the top unit.

Since you have the ML installed, I would turn it on and see if you get any robotic functionality out of the it. Also, there will be a green LED on the top of the picker when you apply power. If the LED is not lit, the cable is most likely no good.