Megadrive Cartridge Slot Widening
The European Megadrive and American Genesis cartridge slot isn't too narrow to allow Japanese cartridges to fit in. You can buy import adapters to get around this, or you can modify the cartridge slot yourself.
Simply take your Megadrive apart, undo the 3 screws holding the cartridge slot doors onto the inside of the Megadrive upper shell, then use a flat needle file to gradually make the slot a bit bigger, you don't have to make the actual slot any wider. You can go for the quick and easy square it off, or you can leave it a little bit curved. Re-attach the doors, re-assemble your console.
That's it really, did you really need to read this guide?!
This will allow most Japanese games to play, for all of them to play properly you'll need to fit some switches. The only negative consequence of doing this modification, is that the doors no longer fill up the actual cartridge slot, so it looks ugly with no game in, and more dust enters the console, maybe you could find something to make new doors!?
