Replacing bias cell on Dickerson amp

[Resonator Guy]

I am currently working on an neat old M O T Dickerson amp with a 6" field coil speaker. There is no volume control. Someone has added a toggle on/off switch and done some recapping. I don't know yet what else has been done. The preamp is a 6SF5 which I have never worked with before. This tube was biased by a bias cell from input jack to grid, pin 3. There was almost no volume so I attempted to read the voltage on the cell. There was none and one lead was almost corroded off. I replaced the cell with a short length of wire and have greater volume wih a bit of distortion.
The cathode, pin 2, appears to be grounded, just with a bit of wire.
Do any of the pros out there think it would be okay to replace that cathode ground with a resistor, say 400 ohms, and a .047 bypass cap?
The other tubes are 6V6 and 5Y3.
I have been searching the web where , of course, one can believe all that one reads and have seen many many differing opinions, so I came here, where I trust the opinions.
Any assistance would be appreciated.

[g1]

Isn't the input circuit the same as your Leilani? I think you went through the same issue?

[Resonator Guy]

Very similar but a different preamp tube, 6FS6 vs 6SJ7, triode vs pentode, with slightly different wiring, (grounded cathode). Just trying to make sure.

[Resonator Guy]

I got it! It won't knock a Champ out of the room but it is pretty good. Strange thing, someone had recapped this pretty nicely but left in the dead bias cell. When I replaced the cell with a wire from input to grid it worked as well as when the cell was in. Took out the ground from cathode and put in a resistor and bypass cap and it works well. I doubt I will stop getting these MOT lap steel amps when I can, but they don't really make full use of the 6V6.