PLAN B analog blog

I've been looking at the voltages from my M24 (Heisenberg Generator) and  I have some questions.  The patch is simplicity itself: stepped or smooth output to my Velleman panelscope.  What I'm seeing does not conform to what I'm expecting from the descriptions and diagrams at http://www.ear-group.net/model_24.html .   According to that (if I understand things correctly) I should be seeing voltages randomly varying from -6 to +6 volts with the Mean pot in the middle and with the Deviation knob clear to the right.

For the stepped section of the module, I only get the full -6 to + 6 when the mean is all the way to the left.

The output from the smooth section almost never goes below zero volts.  Is this how it should be?  At no setting on the knobs do I see a random voltage smoothly swinging from -6 to + 6.  In fact with the deviation knob at full CCW the voltage seems vary between -1.4 to +2.18 when adjusting the mean.

When adjusting the mean knob from the stepped output with deviation full ccw the voltage goes from -9.2 to +10.4.  Is this correct?

Thanks,

Bryan