Cracking cases

Kurt Andersen talks with Marcia Clark, prominent again after two highly regarded television shows revisited her role prosecuting the O.J. Simpson case, and who now has a new legal-drama TV show, “The Fix.” And producer Sam Kim takes on a case of his own: He helps unravel the mystery of an old “Sesame Street” cartoon called “Cracks.” Many people who are middle-aged now remember it terrifying them as kids — and then the cartoon vanished.