Omega Cal. 455 - Rotor removal issue

Hi everyone,

I’m currently servicing an Omega caliber 455 and I’m having trouble removing the rotor.

There is a central disc with a screw. I was able to loosen the screw, and now the disc (and rotor) can rotate freely. However, the screw itself will not come out - it just spins in place and seems to stay captive.

At the same time, the rotor cannot be lifted off.

There is also a small empty hole next to the screw, which appears to be part of the design (not a missing screw).

So currently:

• The central screw is loosened but not removable (spins freely)
• The rotor/disc assembly rotates freely
• The rotor cannot be lifted

Before I apply more force, I wanted to ask:

Is this screw supposed to be captive on the cal. 455?
Does the rotor sit on a friction fit even after loosening the screw?
Or is there another retaining mechanism I might be missing?


Any advice would be much appreciated - I’d like to avoid damaging the rotor or the bearing.


Thanks in advance!

Hi - thank you for your suggestions - they brought me on the right track. I tried to rotate the disk - but it does not unscrew.
But then I recognized that the disk are indeed a two disk sandwitch. In the middle they have a little excenter attached to the screw. The excenter secures the disk via a recess in the central stem. When i turned the screw in a certain position, the rotor was free and i was able to detach it.
The calibre 455 is extremly tiny - so are all those parts… a really challenging project for an hobbyist like myself….
Thanks again!