[Ron Ramirez]

I would leave the pot alone unless it is obviously faulty. Some of these were 6 megohms, others 4, still others had a 6 meg section and a 400K section. The ones with the 6 meg and 400K sections often read open, but work in the radio.

If you look really close at some 1940-41 Philco schematics with this type of tone control, some of these are drawn with a "break" in them. I think there is a very minor gap in the 6 meg/400K controls. And, yes, they will work that way. One section cuts bass while the other cuts treble. When the wiper arm is closest to the plate of the first audio tube, treble cut is at maximum, giving the effect of more bass. And with the wiper arm at the opposite end of rotation, close to the resistor connected to the volume control tap, bass cut is at maximum, giving the effect of more treble.

If it is scratchy or does not seem to be working, try a shot of DeOxit first before thinking about replacement. That one would be very difficult to replace since it has a metal gear attached to the shaft; this metal gear makes contact with "teeth" on the inside circumference of the tone control thumbwheel.