But seriously folks...
That columns selection switch may be stuck or shorted. I'd see if the switch has a nut or fastener that's holding it in the "pressed" position. or someone has flip-flopped the wiring on that particular switch in error, compare it to the other buttons switches wiring. Electrically, they all "daisy-chain" in & out of each other so one bad or miswired one will have an effect on all of the others.
It is also possible that the selection relay for that button is also stuck, it would be located in a long gray metal box that the coinmech plugs into, there is one relay for each selection button & a vending credit relay as well.
Another possibility is that columns
delivery micro-switch is stuck with old soda, & if the machine doesn't "see" that the soda has been "delivered" it will keep spinning that motor until the "cows come home".
Be aware that every switch & relay on these early Choice Vends are at line voltage (120Volts) so be careful.