On the bottom selection and the second to bottom selection of my vendo 407 coke machine it registers as sold out but still gives a pop. If you hit one of these nonworking selections again it will keep giving you up to 4 pops. If you hit a working selection it will give only one more pop. If I manually activate the nonworking selections it seems to make the complete vend and only give one pop.
WhammaJ,
It does sound like jackpotting. Sometimes if the motor brake gets sticky and doesn't stop in the correct position it can make the sold out lights come on. The motors should stop in the notch, one microswitch up and one down (see pic below). And if they stick a lot then you will get more than one can. This link is to another post here that covers fixing this problem:
http://www.vend-resource.com/forum-topic/vendo-480-keeps-vending
Hope this helps,
Frank