Here we go again...!
Apologies for banging on about this but there ya go! The tapping noise that I thought was the CCT is still there. I tried to adjust the chain as per instructions but there was no free play in the screw - so little change there.
I have noticed that its quieter (but not gone) when the engine is hot, and I can induce the sound when riding by opening the throttle even a little - but more so on acceleration. No noise when idling though, only under the throttle!
I know this is a pain in the arse subject but all advice appreciated!