also note that I've posted many, many replies referring to the fact that a lot of earlier multi-vend machines needed to have
ALL OF THE COLUMNS pre-loaded with a minimum number of cans or bottles before they would even accept any coins, this was a separate function from the SOLD OUT switches circuits. this fact has kept many newbies chasing their tails thinking that they have a wiring issue when in fact, it's an operator (loading) error.