I am not familiar with the type of generator but it sounds as though it is a brush type, not a capacitor excited one.
I second that. The brush assembly is a giveaway, as is the printed message about adjusting "pot 2 on the regulator board" and the picture of a circuit board covered with integrated circuits next to a cluster of three small transformers (probably the step-down transformers to power the circuit board and provide it with a stepped-down sample of the voltage).
All that stuff about self-exciting generators doesn't apply. This one has a voltage regulator powered by and sampling the output and providing an excitation current to the rotor through the brushes.
If you have 30v then you will gain nothing by flashing it.
I'll second that. 30v indicates there's enough residual magnetization to get it started.
I agree with blasting things clean, too.
Afterward you might try making a small adjustment to "pot 2" and see if the output voltage follows along. That's probably the output voltage adjustment, or a control related to the voltage input level. The warning is probably because it interacts with the winding configuration such that a change in configuration might cause the unit to overvoltage and burn out the electronics if it isn't re-tweaked before spinning - and to avoid people frying the machine they tell you to turn it to a safe setting when changing config, then bring it up once you're spinning, according to the manual's instructions (which may have more details on how to do this safely and correctly).
You should try to get hold of the manual if you can, before fooling around with it. Contact the manufacturer for them. They'll probably be helpful, and the manual is likey to cost much less than fixig something you break by tweakig without it.
Also: What is the history of this unit? Did you get it "AS -IS" with no info, or do you know how it got into this broken condition? The more we know, the more we can help, and the less likely we'll tell you to do somethig that breaks it.
