@lewm There is no way that tonearm wire is as thick as 33g! One can see the insulation, but one cannot see the wire inside it when looking at the end cut. I have a wire stripper that can strip down to 32g, but that insulated wire slips right through it.
As for wire gauge affecting only resistance, that is not true. The math for calculating inductance is complex, but you can find inductance calculators online to determine the inductance of a wire. The bandwidth numbers I posted above are just from that calculation.
Also note that wire has a surface area just like capacitors. Put them closer together, the capacitance goes up. Make the surface area larger and the capacitance goes up. Move them apart, capacitance goes down and inductance goes up. The fact is, resistance, inductance, and capacitance are linked together. Changing one will alter the others.
I do have a milliohm meter in the lab, and it uses a 4 terminal Kelvin measurement. It can easily measure 0.001 and 0.0001 Ohms. The catch is it pumps 10 Amps down the test subject, and it measures the voltage drop to display milliohms. If I pumped 10 Amps down that tiny wire, I am sure it would smoke it! Frankly, I would be squeamish about sending a 1mA as a test current. The only way I could measure the resistance in that tonearm is to determine the lead resistance and subtract that from the reading. Indeed, a process fraught with errors.
The best approach would be to just replace the wire with a known & larger gauge I can't do this in the lab, and the quotes from folks who can do this is more than I want to spend on the project.

