Having recently obtained a 1930's two-pole knife
switch an a porcelain base, I decided to make use of it
in my own shack. Seeming to be of copper, on inspection
it proved to be copper-plated brass. The rivets forming the
hinge on the knives were loose and could not be banged-up
so I drilled them out and replaced with 2BA screws plus
locknuts.

So, now I can earth the G5RV when it is not in use, and
disconnect it from the TX.

It brought up something interesting, and that is,
that one half of the G5RV produced no signal
on RX - perhaps in the recent winds when the
lilac tree blew over (Quod Vide), one of the connections
from the co-ax to the ladder sections has fractured; that
remains for investigation.

This is thin coax which has been installed for about 22 years.

I was intrigued to find that both the braid and the inner conductor
were blackened, despite being on a section of the cable that could
not have had water ingress. Perhaps is time to replace with some
larger diameter coax?