Well, please don't take this the wrong way, but I don't think rewiring the machine will increase the value that much, or at all, so I would'nt spend the extra cash on that.
I say that because unless it's someone that has no idea about these machines, there are far too many things wrong with the machine as it sits to command a price that I think you might be asking.
For someone that just wants a coke machine for his/her mancave and doesnt care about the details, then if you rewired it, that can be a selling poin to them, but that's about all it would be.
The paint on the machine is amature at best (the bottle door is painted over, the inside has rust bubbles painted over at the top etc...) The Coke lettering looks like someone did it with liquid paper, and bad at that. The motor was not touched at all, which might be in this case a good thing lol
As well, the black rubber seal that goes around the door was painted red too, as if someone just painted the machine as it sits.
I won't downplay the machine more than that, but I bring it up only because you asked about if you should rewire it to raise the value, and Im just saying that the machine needs to be stripped down and re-done properly, so let someone else rewire it, and save your cash, and just list it at a price that you feel comfortabe with, and see who bites.