Re: Poor instructions
No, portable players with a slot you put the disc in, with a button to press to eject it, didn't have an autochanger. Some models were for children, but there were models for "adults" too. Maybe some high-end model had an autochanger, but I never saw one.
Probably I also tried when I was four or five to put more than one disc inside, but guess quicly understood it didn't work and just jammed...
My father disc player had an autochanger, just it worked almost OK with LPs (but when I was a teenager I was horrified it could damage my precious discs...), 45 were too light, and probably the larger hole created more friction, and often they didn't fall when was the time, or fell too late over the arm. That's why, I guess, they quickly went out of fashion in the '70s when hi-fi systems became more sophisticated.
But those didn't have a slot to load the discs into. All the ones I saw had a spindle you loaded with discs, started it, and prayed it worked...