If you can't find the key, you're going to have to drill the lock at some point anyway. Best to do it before you move it, and move the game with the head off. With modern cordless electric drills, you can almost drill out a simple back door lock faster than you can open it with a key.

- TimMe

I always have very good luck using a small diameter drill bit as it is very fast and doesn't make much of a mess. 5/32" is my preferred bit size, but anything around that should work. Avoid anything larger than 3/16" or you'll just be drilling out a bunch of the lock barrel for no good reason.

Be sure to use a nice sharp drill bit, dull bits are not good for this task. Also, since you're cutting metal, you'll want to put some kind of lubricant on the cutting tool. If you have cutting oil put that on the drill bit, otherwise just put some 3-in-1 oil on it.

Run the drill bit right into the center of the lock and go straight back. 99% of the time, the tip of the drill bit will zip down the nearly empty middle of the lock barrel in about 1 second, where it will hit the mounting screw for the lock tab and unscrew it instantly. This will cause the lock tab to fall off the back side of the lock, and you'll be done.

If you have one of the 1% unlucky locks that won't drill out this way, then you will need to start running larger and larger bits down the center of the lock until you get it.

When I'm drilling a lock at a customer's house, I always throw a shop towel on the floor below where I'm drilling to catch metal shavings and oil.

- TimMe

This. ^^ The customer has lost the keys, remember? So the lock has to be replaced anyway, and locksets for games are cheap.

Locksmithing is obviously very useful, and I admire the skill set, but I don't see any advantage to applying that much expertise in this context. I'm not a locksmith, and it's unlikely I would be very good at it.

What I'm really good at is fixing vintage coin-op games. Just this year alone, I've had to replace about 20 game locks due to lost keys. I don't want the first thing my customer sees is me futzing around trying to pick a lock for 10 minutes. A cordless drill and 3 seconds later I'm in the machine and making repairs, which is why I'm there. I really don't think that, for my situation, this is "doing it the hard way."

- TimMe