I see your problem - dogs
should always be facing starboard during steering
system inspections, not port. But at least it is standing at attention, as also necessary.
That cable looks old enough to be original, so if it is 10mm, then I would just replace it with the same.
The stuff only costs $1.50 or so per foot, so it isn't like you will go broke with it or sink your boat with the minor weight of it.
Your chain looks fine from the picture.
From your previous picture, that wire absolutely failed from chafe. It should be pretty easy to figure out where/why - just look at the area it chafed in and see what is doing it.