Have you checked your speedometer? Sometimes on Split Window Typ 2s as
well as bugs, if there is some corrosion on the bulb holder unit on
the back of the speedometer (where the turn signal, gen and oil lights
are) the circuit will either ground or get sufficient feedback from
other lights, that the generator light will come on. It happened to
my '56 shortly after I put it back on the road. Its worth a check.

Ric