Good news! The situation has now progressed. I managed to get a screwdriver that fitted the really tiny screws on the backplate of the Amiga A1200 keyboard. I soon managed to remove all the screws and put them in a safe place. This place is actually in a plastic glass with another plastic glass inserted into it, forming a small compartment.
As I removed the backplate, I was just sitting on a sofa, bending over a low table, then as I detached the backplate from the keyboard, some small components fell off and onto the cushion I was sitting on. I hope I managed to grab them all, but I'm not sure!
When I was trying to push out what may have been the remains of the X key post, suddenly something shot out and landed to the right of my sofa, but when I looked I couldn't see any sign of it. I think it would take a search party of nanobots to find this, as well as the spring that was under the X key, and the Micro SD card from my Android tablet!
I'm attaching some pics which show everyone the current situation with this keyboard, as well as the components that came out of it. There are some coins in the pics so that people can see the size of the components. The coins are the British 1p and US 1c, both often called “a penny”. I didn't have any Euro coins handy. I want to repair it myself so that I have more control over my life. I hope you can understand this!
I look forward to any and all suggestions you may have about how to finish the repair. I think I'll probably be buying the components that Spirantho has offered in any case, to restore the keyboard to perfect condition, even if I never use that blank key. I also want a key that says X on it!
If or when I manage to fix this, then who knows what my next project could be?