Cable issue, try redoing the connectors first.Is CNN Int on 11671H in the clear? My Vu+ Duo 4K receiver is not tuning in the channels on this transponder but channels in the high band are working ok. There was nothing wrong with the LNB back in May.
Going up a ladder is not an option.If money is tight then try inverting the LNB on the clamp.
Sometimes water gets in the cap and then down to the electrics.
It is possible.Could be the thin coax shot gun cabling failing aswell?
I receive some low band channels but they are weak and keep losing signal.Have you lost all low band transponders? CNN is on the Europe beam so is weaker than those on the UK beam such as the BBC channels, if you can still receive those it may be an alignment issue.
Two ladders then.Going up a ladder is not an option.
The whole installation is nearly 10 years old. I tried to get a multi LNB dish installed roughly a month ago but one installer refused the job and the other installer didn't even bother to turn up giving excuse after excuse. It is almost impossible to find an installer around here who will do a non standard minidish install.