I have two IBM KB-8923 keyboards, the best possible quality pure rubber dome you can get, and I can't open them!

I unscrewed all the screws, but, if I pull one side; the other side gets stuck down, and vice versa. These things don't even NEED screws to hold them together. Unlike the more pronounced "lip" on the bottom of Model Ms, these sink down, so, you really have to dig your nails to pull the bottom up; which is why the sides are kind of easier.
I'm trying to open my first one, since, it's VERY dirty (it was the keyboard I used all the time for everything for 13 years). I pulled out all the keys usually to clean it, but, I want to take it all apart, and clean every inch.
Heh, the arrow keys on it are so worn out, that, even the labelling is coming off very slightly, and, you can rotate them in circular motion. I played every single game I own on those arrow keys, so, that's pretty good. NONE of the labels otherwise have worn off, which is absolutely amazing. I typed laods on that keyboard.
If you want keys that will
never wear out, use KB-8923 key stems.