Ok, it's a very busy day for me but I've managed to take some photos of the switch. It was quite a challenge to open up the slider, it's one of those one-way, "assemble-only" designs. After a long examination I concluded that there's no non-destructive way to take a peek inside. So I've took out one of the Shift keys - 2U size, with two sliders beneath, and opened up the "dummy" (the one that didn't have a reed register). Well, the hard plastic case chipped on top, as expected... anyway, I took requested photos and glued it back together with methyl ethyl ketone. Good-as-new. On the first photo you can see that the register is absent in one of the holes. Notice how thick are the cap walls!

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@dorkvader: I've also noticed the "extra" places for more switches. I'm not that experienced with vintage boards, but I think I saw something like that before in a KME board (ALPS switches). Nice catch! Also, I've visited the webpage you provided to compare Zbrojovka machines with Tesla. It seems that 262 design utilizes different switch... But...
But it really does not matter right now for me. What matters is that it really blew my mind to see all those vintage boards!!! Especially
D2770 - it's just sick... Talk about complicated! Sorry guys, this is where I draw a line

This is WAY out of my league. I'm just a simple folk from Eastern Europe, fascinated with old equipment, that's all. I'm pretty good @ visual refurbishment & basic electric diagnostics but this "XT conversion" was rather a casual question

To be honest, I suck when it comes to handle soldering iron. Don't have much brains nor patience to walk that road.
I'm thinking what'll be my next move with the boards... Classfields maybe? On the other side, what I'm definitely sure of right now is that I have to bring Elwro Junior home computer and the other reed switch keyboard (MK45) to my home and take some pictures... You guys 'll have some fun. MK45 is a blast, and I'm sooooo sure it's uniqe as hell (only about ~50 units of this computer were produced). And, what makes me a little proud - it was made in Poland

Anyway, so many thanks for your curiosity about those boards! If only people in my country were half as interested in vintage hardware as you... The World would me a better place.
EDIT: Fixed links pointing to my server, as old hosting domain does not belong to me...