It is only that I have had experience with the disease that I am suggesting
that, perhaps, the stammer that Ed and Christine experience is a form of
OCD, Obsessive Compulsive Disorder.  As I understand it, in the brain of
people with OCD the switch that indicates "enough" is not turned on, so
people feel compelled to to repeat certain actions, like making sure the
door is locked or the gas on the stove is turned off.  Perhaps the need to
repeat chords while playing the piano is a symptom.  This description is,
of course, an oversimplification of a complex problem.  I, also, want to
stress that people can be obsessive and compulsive without having OCD.

Ron Chaplin