Murphy A24C.

[Murphyv310]

Slider to Grid..... normal practice Jeffrey.

Yes, but it was always a cheapskate bad idea as it's unreliable and noisy compared to adding a capacitor and resistor. Especially as the pot wears or gets dirty.

Lots of things were or are "normal practice" but a bad idea.

There are relatively few sets with the addition of an extra resistor and cap. The current through the grid leak is microamps, controls go noisy even if you add in the DC blocking cap.
Like I already said C33 is a much bigger issue than strapping the slider to Grid. A cooked output transformer is a major discrepancy, than how the volume control is wired.