I got this non-working 24-hour Raketa; the dial itself is in good condition, but it’s missing the second crown to rotate the ring with city names, the glass is broken, and it doesn’t work. I never took one of these apart yet so I wasn’t sure what I would find.
It quickly became apparent that the stem was stuck and couldn’t be removed, so I started disassembling the movement inside the case. Apparently someone used salad oil as lubrication – or some other inappropriate oil that polymerizes on oxidation – and it had turned into a solid sticky goo mixed with rust :/
The good news is that this side looks entirely interchangeable with any other Raketa 26** movement so any part that’s too far gone could probably be swapped out easily.
Eventually I got the stem out, and the movement out of the case. This is the back of the dial, the “world time” bezel, and the dial side, where things get interesting:
This large retaining plate is, as far as I know, unique to the 2623. On first glance it’s immediately obvious that the hour wheel is about twice the size of the one on a regular watch. So this is how you make a 24 hour watch; a different base plate and 2 different gears, everything else exactly like a regular 12 hour watch.
This is the dial side of a 2609 for comparison. The relevant difference is the size and position of the brass colored gear (and the hour wheel which is not present in this photo but you see the recess where it fits):
And here it is right after cleaning and swapping some parts:
