Speedometer evaluation?

About oiling the shaft. I use a razor blade to get under edge of that plug, work around and pick it out. I use a needle to pick the wick from the hole. I can wash the wick and bore too with brake clean, allow to dry and relube with 3in1 oil. The natural table lay of the instrument allows excess oil to drain at rear. Is it necessary? I don't know. I know all this disappeared in later examples. bump in casting remains. the hole, wick, brass plug,,, gone.