Hmm. Looks like the Cludor was designed with internal sync, while the Vebur needed it added (either at the factory during manufacture, or aftermarket) as did the Compur-Rapid. Still seems odd that it would be X with that trigger, but I'll try to turn up one of my strobe adapters (hot shoe adapter with a PC cord) or a strobe with a cord built in, or the plug-in sync cord for the one strobe I have out, so I can test the shutter. If you see the shutter fully open with a strobe, it's X; if not, it's M (or in need of repair). You can also use the strobe to observe the position of the cocking lever when the flash fires to confirm.

