Jeff Allen wrote:

Thanks for the advice but it's actually leaking around the coupling
that's integral to the cylinder, i.e. the bit that comes pre-fitted to
cylinder rather rather than compression joint.


Yes, I can see that. I didn't mean remake the compression joint (which
you'll have to do anyway). I meant undo the flange fitting, clean up,
apply sealant, redo.


--
Grunff