Gary, good find on the BOL light. All the times I took a computer service call to find a light source askew from the sensor. You might try rectifying the 6.3 v into a 27 ohm resistor then 4 1N4002 diodes in series. Each diode has about .7 volts drop, should give you 2.8 - 3 volts constant. Oh, you'll probably need an electrolytic before the resistor, maybe 100 mfd 16 volts.
Hi Rod, Thanks for the advice.
I've done some further testing and found out that I can get the exciter light to illuminate. I had to turn the compensator (part 11B on the schematic) all the way up as far as I can get it without forcing it. It still isn't quite as loud as using 2 @1.5 vdc batteries = 3v. Close however. Maybe the compensator is going bad. When I am adjusting it without the lamp connected, but connected to a volt-ohm meter, I seem to be able to adjust the ac voltage well past 3 vac, but it seems a bit inconsistent. But under load conditions with the meter I get about, maybe 2 volts.
It looks like a tuning capacitor on the schematic. Unfortunately I do not have and specs on this component.