Raising max contrast

[lnx64]

How do you raise the maximum contrast, if the chassis doesn't have a subcontrast POT?

Since lowering the G2 voltage to prevent the red flickering on the dark screen (as lowering the BIAS or drive didn't do anything), while my maximum brightness is still very bright, my contrast has to be turned all the way up for a normal picture.

PS: The drive controls only have two POTs, red and blue, no green pot.