Did you all notice that the wires entering on the left appear to be SO CABLE!!
And they appear to enter the lower left corner of the panel without any sort of bushing or other protection.
I often find systems here in which the original 1950s/60s insttallation was just fine, but the extensions and modifications to it in more recent times are the problem.
It looks to me as though this might be a similar sort of situation.
