@Guppycur and
@Jost Amman you both may have missed the whole point that the new "vending" machines aren't supposed to work the way the old ones did.
see the detail here:
What you see is an old fashioned coin slot.
There are no coins in 7D2D.
Just dukes, which are casino tokens (chips).
These won't fit into a coin slot, or if they did, they'd jam the whole mechanism...trust me, I tried that many times as a kid with low allowance.
But there is that keyhole right under it.
So you will be able to lockpick them, and then the whole thing is open.
Absolutely no need to press any buttons at all, you just pick that thing open, and then grab all the goods you want...even those with the "0" that you can't select.
damn, I even bet this was one of Roland's puzzles.
Pickable vending machines confirmed for A21!