I have put a pic
here
The two resistors above are from a) the plug which was totally O/C at 1kV and b) from the plug which was the lowest resistance. One of them shows a little bit of burning at the ends.
BTW the resistor is described as "silicon carbide" here, page 3
here
A google on silicon carbide resistors reveals these are not normal resistors, e.g.
here
Resistors which pass a current proportional to the fourth or fifth power of the applied voltage are now widely used in many fields of electrical engineering. The first part of the paper discusses the behaviour of these resistors in terms of the characteristics of single contacts between silicon-carbide crystals. In the second part, the construction and properties of the resistors are described, and some typical examples are given of their uses for protection on transmission lines, in d.c. inductive circuits, in radio, for spark quenching at relay contacts, for voltage regulation, for field control of electrical machines and for various other purposes.
[my bold]
It's no wonder that these don't measure as anything useful at low voltages, but one would expect more consistency...
However it is quite possible that these resistors do basically nothing useful at sub-kilovolt voltages, so measuring them as described may well be a complete waste of time.
And the turbo Cirrus failures have to be a separate issue anyway; there is no way the cracked insulators can be anything to do with the resistors.