I did an auto calibration and it went through fine with extruder 1. When extruder 2 tried to touch the cube it kept pressing the bed down (scary down) and then when it tried the side touches it went really nuts in how hard it pressed. In looking at a video I made it showed a tiny bit of filament oozing out. I found in the ohai (I might have that acronym wrong) the details for calibration and one of the things it mentioned was not having filament loaded. So I took the filament out, cleaned the nozzles well with the brillo pad thing while heated to 170c and then it worked.
HOWEVER :-), no where in the normal course of what I would think a user would do is this clear. I happen to trip across the ohai doc, but I doubt the average "just go buy a printer and want the functionality to work user" would find this.
Suggestion: How about not allowing the auto calibration to be run unless the filament sensors detect no filament. Additionally, while I know there is not a lot of space in the LCD screen for messages, how about in addition to the detection ensuring no filament loaded, giving some message about "unload all filament, use brillo pad and clean tips at 170c before running calibration". I don't have the answer, but I know the current setup is not friendly. :-)