Appreciate if you do find the 955.41x, as it looks like this movement is ‘in need of a service’ after all. It has lost two minutes since yesterday, which is disappointing/totally expected.
Balls. I'm just getting a train up to Edinburgh just now, so will check again when I'm home. In the meantime, you might get it working by dripping some naphtha or similar onto the jewels.
I probably have a 955.41X movement in my spares, and likely have a black date ring. Will have a look.