Quoted from PhCor6:Could that be the original door or has it been changed, this will be my first Pinball Machine
Back in the day pinball machines were like buying a new car. You could start with a "base machine" then add features like the second & third coin slot for additional cost. So a single slot coin door would just have been a slightly cheaper machine than one with two coin slots. It looks kind of odd since most machines have at least two but not all of them.