Any ideas please?
Also, as an aside, where the large hexagonal 'nut' (at the very rear of the pic) goes into the tank itself - this had some moderate sized rusty flakes on it which I've now removed. What can I do to prevent this rusting any further? Spray it with WD40 perhaps ???
Or is a bit of rusting to be expected?
I want to avoid any possible leaks from that area in the future!