Product review (5 stars): Sketch to Plotter: 5 mins
Worked right away.  Seems to have the sensitivity I need.  Still playing with absolute values.

Update: when values came back 1 or not a number, I checked the cable before blaming the sensor.  It's a tough board, surviving many inadvertent assaults.  Following specific advices, I didn't have to put in a pull up resistor, as there are only three leads and 5v  Vcc is ifne.  The best kind of toy for kids.