Last Monday I worked a little bit more on this keyboard. I decided to start on the wiring. I did the rows, and then I decided the keys are not sitting in their holes well enough. So I decided to do what I did with my previous two keyboards -- glue the switches in place.
Unfortunately, this time I used instant glue, and applied it when the keyboard was up-side-down, so that the glue got into the switches. Sure enough, they are all glued hard, and there is no force that could budge them now. I suppose I could try removing them, opening each and cleaning, but they would never again work as well as before, and I honestly don't have any stamina left to do it.
So I'm aborting this project, with a small possibility of reviving it if I get my hands on some spare switches again.