This is only a theory, however after viewing the News Flash from the Mummenschanz episode of TMS I reckon this sketch was taped around about June 1976. There are three "versions" of the Muppet News Man; the first version the character's eyes are half-closed, the second version the eyes are wide open and the third version the eyes are wide open and the character is now wearing glasses. The version in the episode is the second, which was first introduced in the Rita Moreno episode. In terms of props, the red phone on the desk in the Mummenschanz sketch is on the Newsman's right-hand side; this is the same side as in the Joel Grey, Ruth Buzzi and Harvey Korman episodes (ignore the Connie Stevens episode sketch, that was taped much later). From the Paul Williams episode, the phone is on the left-hand side. In the two Joel Grey sketches, there is no sound effect as the Newsman comes onstage. There is a sound effect in the Ruth Buzzi episode, however that is the sound of a teletype machine rather than the familiar sound effect used in most Muppet News sketches. That sound effect is first used in the Rita Moreno episode and it is used in the Mummenschanz episode. As I say it's a theory only, however I think it's a pretty good theory.