This past weekend-Noggin showed an episode from 1972 and it had SAM the Robot on there. He was going to Mulberry Street and assumed Sesame Street was that--he had a date with Shirley the cement truck. Now this must be or at least near to his introduction because in this street scene Gordon and Susan are awestruck with him, and somewhat rather startled, introductions between Gordon(HAL Miller) and Susan to SAM ensue and he introduces the audience with his main Character flaw--Robots are machines and they are perfect--don't make mistakes, well needless to say, SAM doesn't get anything right, in his robotic somewhat rather scary, synthetic voice he repeats like a broken record until a human beats him on his pot -metal mandible. As to who did his voice it is hard to identify, at the time Jerry Nelson and Spinney were both dawning big burly uncomfortable costumes so it could be a toss up. I am not sure if Bob Magrath did the voice on this skit, but I am not sure as I have no evidence or literature to say he did or did not. Therefore this topic is still up for discussion, just thought I would post my review since this was the first time I ever saw SAM on an episode as he was long gone to the sesame scrap-yard before my time to acknowledge the show after my birth in 1979.
Jeremy