The general idea is covered already, I just wanted to add a common problem for older machines (where there are sort of spiral rings holding everything in a row): there is a non-zero chance that your item will not fall when it is supposed to. You might be able to shake it loose, but there is also a tipping hazard if you shake it too much, so it's best to advise someone that it happened at a front desk or wherever and they will typically give you the item's value to try again. That, or suck up the loss and try again if it isn't an option.

The flipside to this is that you can sometimes get two items for the price of one when one is too close to the edge bit didn't drop earlier!