[CamJam]

I'm in the process of replacing my CSB and giubo, and have managed (with much difficulty) to start removing the insert nut with a 50mm thin wrench. It seems that as the insert nut (green arrow) is loosening, this black metal ring (red arrow) is deforming. Thought I'd better stop and ask advice before I bugger something up. Is the nut supposed to fit inside the ring as you back it off, or how does that work? Seems like the driveshaft should move forward as the nut is loosened, but I think the giubo (which I've read should be removed after the insert nut) will be providing some resistance. Any advice on how to proceed would be much appreciated.

Geez, this nut is stubborn. I'm wondering if heating it up with a heat gun would melt the loctite enough to make it easier?

EDIT: I see from the Bentley manual that this black ring is a retaining clip, but there are no instructions on how to remove it. I assume that it must not be a continuous ring if you're able to remove it, but I'm not seeing any break in the metal anywhere. Any hints? Looks more like an oil seal to me, but none of the diagrams I have show one at that location.