i dont know how picky thoose voltages are on pin 6 and pin 7. if that is the problem it should be cause of a bad or wrong resistor:
otherwise, if the chip was having an internal short, you would prob not see thoose other correct values.
do you have a scope?
try alos connect an external synth/machine into the mix in jack and see how volumes are out of mix out and phones out.
if thoose also are off, your problem might be further downb the line (mixer part for ex).
my machines kills fascists!