Generator light

[Surfdaddy]

since I got my truck running The gen light has been on, kind of dim and brighter as the RPM's go up. While driving the signal works pretty fas and slows as the rpm's solw. I measured the voltage and it was 13.5 volts at idle. I figured the regulator was going bad so I changed it and now the voltage is now 12.6 wich seem low. The light is still on but stays the same reguardless of RPM, (on and pretty dim). Everything seems ok and it's been so long since I messed with a generator, but, I think I remember that you may have been abe to adjust the voltage by adjusting screw on top of the field coil. Is my memory right or is is just wishful thinking. I thought the regulator was bad and the light would go out but now I'm kind of puzzled.