This is a game show that probably has to be seen to be believed, and it may be the quintessential television artifact of the 1970s.
The first round was a fairly normal question-and-answer session involving two contestant/celebrity teams. Asterisks scrolled across an electronic display board representing the number of letters in an answer, and host Art James read a clue to a person, place, or thing. The asterisks were replaced by letters one by one until one of the teams could buzz in with the correct answer.
The first team to answer five correctly got to play the bonus round, and here was the item the show was named for, an astonishingly large pinball machine that sat on the studio floor. The contestant operated one flipper and the celebrity operated the other, with the object being to keep two balls in play for 60 seconds each in order to hit bumpers and other targets for prizes and points (each bumper usually represented half a prize).
If the team managed to reach a predetermined point value, which decreased every game when it wasn’t reached, the team got to play a bonus ball that would score various dollar amounts for the contestant.
"Magnificent Marble Machine" aired on NBC at noon Eastern time from July 7, 1975, to June 11, 1976. About halfway through the run, the show changed to an all-celebrity format, in which the celebrities were playing on behalf of the studio audience. It was fairly expensive to maintain and operate the gigantic machine, and apparently, viewers would rather go to the arcade themselves instead of watching someone else play pinball.