Check the brown wire circuitry.
From the ign sw, there is a brown/white wire to firewall connector, approx. 30 ohms resistance for the length.
You will have to remove the GEN bulb to measure as the GEN bulb is a parallel path, with bulb in place, you will measure bulb resistance, a lower value than the single wire.
Next measure the brown wire from the VR to the firewall, or better yet, the light socket on one side as it should be less than one ohm.
When ign on, engine off, one side of GEN bulb has ign power, the other side/contact is lower value, hence a glowing GEN bulb.
Engine running, VR brown supplies power from VR relay of equal amount of power and GEN bulb goes out.
If there is a difference of voltage in the two powers provided, GEN bulb dimly glows.
With a warm battery, VR cover temp of approx. 130°F, battery voltage should approximately be 13.8 volts, no accessories on, VR may be adjusted alittle high.