You can buy new ones dirt cheap, probably less than trying to rekey. I think pinball life sells lock cylinders that usea common key.

Here's what you do: Pull the plug (core) of the lock out. Put your key in it. Note any pins that protrude. Rip those pins out with pliers (a little spring will come out too). As long as you have at least one pin left, you can put the lock back together and it'll work fine. This is assuming you're just looking for a working lock for your game, and are not concerned with security.