Since Yamaha is a Japanese company, their synths were likely made (or at least designed) in Japan which uses the metric system?of measurement and construction for everything, including screws, nuts, bolts, etc.

At some better hardware stores (not always the big box hardware stores) there are metal or plastic rectangle thing you can hold in your hand, called a “screw checker" that have different size screw holes in them that you can gentle try out any kind and size screw in to find out what that the type and thread of the screw is.?

America is the only country in the entire world that has a non-metric older different screw-thread system called the "American Standard” system, and complicating things even worse if that there's?two of those kinds of screws within the American Standard system?also: ?"Course” thread and “fine” thread. ?

But the influx of foreign made items sold to America has been increasing since the 1960s, and so more and more stuff now common to us is metric instead of American Standard.

So there’s a metric screw-checker for testing metric screws and a separate screw-checker for testing American Standard screws. ?Both are worth buying and keeping for situations like these. ?

Once you've got those, it's likely your DX7 is metric, so get out your metric screw-checker and unscrew one screw from your DX7 that’s closest to the missing screw holes and then test it on the metric screw checker to figure out what the thread is and write that info down. ?Then measure the length of the screw with any American ruler. ?Let's say for the sake of discussion that the screw is ?half an inch long. ?Write that down also.

Now, try that screw in each of the other holes that don't have screws and see if it tightens up properly. ?If not, you now know you need a longer screw for those holes.

But if it tightens up, now you know what length of screw to get, and that it's metric, and what metric-thread you need.

Put that screw back into the hole you got it out of and head back to that same better hardware store and tell them the exact kind of screws you want and they might have then and then back home screw them into your DX7 and you're in business. ?

Also note that these kinds of screws are called "machine screws” as opposed to “wood screws" or “sheet metal screws" or "specialized screws” of which there are many kinds.

Does this help any?

Catch ya later. ?Bye for now.

Dan Fiebiger.

Portland, Oregon

(Still using my first generation DX7)