The cannon is loaded by shooting the ball into the open locker. You can open the locker three ways
Once the ball is in the locker, it'll roll down under the table, and once it's sitting on the kicker, the cannon will light up and turn from side to side. Some of the shots on the table will be lit, and you'll be offered an award for hitting a lit shot. You press the fire button to fire ;) If you miss, the locker will reopen, and you get a 15 seconds countdown for an "instant reload." Whether you make the timer or have to reopen the locker, you shoot for the same award until you manage to collect it. If you hit your shot, or one of the lit diamonds, you get the award you were promised plus a letter in "Sink Ship". The awards, in order, are: