I have a six cent VMC 72 and the coins go through the rejector and fall into a slot of the coin mech. The coins push up on levers or cams which allows the handle to rotate and vend. If you are missing one coin, that lever will not lift and the handle will jam and not rotate. I haven't looked at it in over twenty-five years, but I believe that's how the VMC 72 6 cent machine worked.
Either coin any direction, lol, will work.
When I was in my teens I bought this and decided to spray the coins with WD-40 before I put them through so it can lubricate the coin mech.
That's what I called the rejectors back then.
Yep, that was stupid. I never had an issue and I never cleaned it afterwards. I definately wouldn't recommend that. This was just a stupidity story for grins.
If my rejector is acting up I usually take it apart, clean it, and polish the metal. I just got my jukebox rejector to work. I was told that the dimes and nickles never worked in it....they do now.