I have bought a number of Casio watches over the years. One of my favourites is the EDB-600 which I still use today. It is a great watch, yet it does have 3 problems:
1. The keyboard is the worst of all my Casio calculator watches. It is made of a soft rubber and the writing wears out within months of use. I have already had it replaced once by Casio, but it is worn out again. Why put such a pore keypad with such a good watch?
2. The keyboard should have had an extra row. When you want to multiply, you have to press the bottom right button 3x - very clumsy.
3. The buttons on the side tend to get stuck. Only thing you can do is unscrew the back and use a screwdriver to push the button out again.
I have attached an image showing the watch from front and back. Your info page states it has the module number 2561 but in reality, it is 2551. I do have the manual for this watch (PDF), but do not know how to “get in touch” to submit it.
I could not find any contact form or email address on the website. I would have attached it to this post (it is a 1MB PDF), but this forum only accepts attachments up to 150Kb!!!! Why is this so restrictive, I run a forum myself and allow 32MB attachments. 150KB is too small to even attach the manual. I strongly suggest you make it easier to submit missing manuals, I very nearly did not bother to join this forum and am now frustrated that I cannot even submit the manual this way.