[Nobbylad]

Hard to tell from the vids but does sound like the CC problem on the K5 I had. FWIW, I put a new CCT on, only to have to renew the CC itself. Not a majorly difficult job, although does require dropping of the coolant, oil, new gasket seals, something to remove the stator etc. It's more of a time consuming job than rocket science and I did have the mechanical know how of YC to guide me.

I'm not familiar with the curvy/manual CCT's, however have a spare pointy/automatic CCT if you're interested.

EDIT: It costs around £150 from memory to renew the cam chain and all the gaskets (pointy).