Cabling for pennycap system

[kragby]

I found a good article on trobleshooting pennycap. It was working fine until I got ACF50 corrosion treatment when both guages went to zero. The oil is apparently somewhat conductive or it change the capacitance or some such.
The article describes that the shielded cable to the probes has to be high impedance so I'm trying to find out what that cable is - I assume a coax but not
75 or 50 ohm standard tv stuff.
I tried cleaning the connections with contact cleaner but to no avail so I am planning to replace the cables completely - just need to know what they are or what has high enough z. Article also says the resistance to ground has to be over
1 million megs so I would guess that is determined by the dialectric in the coax.