Lots of excellent advice in here. Only thing I disagree with is OK Babys are surprisingly decent, but you'll struggle to find parts if something cosmetically happens. Avoid all the other clone cabs though, they're a real mess.
A bit off topic, but I've been looking for an OK Baby for a little while now since I'm from Taiwan, and it's good to know that they seem to be decent cabs despite being a clone (of the Kyotaro Excellent from what I've seen). The last one I saw in person was briefly in Taipei Xinmending several years ago. I finally saw one FS local to me, but it was in such terrible condition (multi color rattlecan special) that I didn't pursue it due to fears of hunting for unobtainium parts and the cost/time of working on the body. I have a potential lead on another so the hunt continues...
Besides being JIS, another thing to consider when working with screws on the Astro City that took me by surprise was the amount of self tapping screws being used throughout the body. Be very careful with these screws, since you could not only damage the screw head, but the actual cab body itself if you wrench too hard or at an odd angle. Be sure to take a close look at the operators manual (widely available as a PDF on places like Arcade Otaku wiki), which has detailed diagrams on what type of screw goes where. Sometimes arcade operators use the wrong screw on these self tapped holes during field repairs, and jam machine bolts (which have much finer threads) into the body instead. This happened to me around the rear marquee area when I was going through the process of cleaning and repairing my cab.
If you experience a jammed or damaged screw, you may need screw extraction pliers like the Engineer PZ-58. I would highly recommend grabbing these for your toolbox sooner than later since I definitely wished I knew about it in my early days of owning cabs. It would've saved me a lot of pain, swearing, dremeling, and WD-40.