Best bias pot circuit for 62 Bandmaster & 63 Bassman

[Underwood]

  Wondering what the best way to add a bias pot to a 62 Bandmaster and a 63 Bassman. Maybe a 22K resistor with a 25K pot? Or with a 50K pot? The schematic shows no resistor coming from the blue and red wire to the diode, but both amps had 100K resistors. Then there is the 15K resistor in between the capacitor. Should I take the wire off the cap and put it to the pot, then solder the 22K resistor to the pot wiper and the pot casing?Any help?   THANKS!!