Re: Poor instructions
If you look at 45's during the era of auto-changers, you would see that many of them had a circular 'bump' track between the innermost grove and the label. This was there so that when they were stacked, they would 'lock' together, preventing the upper ones from slipping while being rotated through a stack of lower disks.
What was more interesting is that the number of the 'bumps' was such that when viewed under a bright mains filament light while spinning on the turntable, they should appear static (strobe effect) if the turntable was running at the right speed, but you had to look very hard.
I have a copy of Tommy by the Who, which was a two LP set, which had sides 1 and 4 on one disk, and 2 and 3 on the other. This was so that you could play sides 1 and 2 on an auto-changer, and then turn both disks over together as a sandwich to play sides 3 and 4.
Mind you, the weight of the records falling down the spindle, especially the heavier vinyl used in the '60s and '70s was such that I was always surprised that the turntable survived. I suspect that is why the BSR decks (at least) has spring suspension to absorb the impact, not for any audio isolation. My Grandmother also used to use the auto-changer on her PYE Stereogram (about the same size as a small sideboard) for shellac 78s which were really heavy.