It's worth testing it yourself - you'll learn something new and you'll be better equipped to deal with any future problems with the generator/voltage regulator

Try the following steps:

Engine & ignition "off".
Disconnect the dynamo red wire at the voltage regulator
Disconnect the dynamo green wire at the voltage regulator, and earth it.
Connect the voltmeter to dynamo red wire, scale 0-40v DC.
Start the engine.
You should see the following...

At idle: around 5-11v, depending on idle speed
At higher revs the voltage should climb rapidly above 20v

If the voltage remains below 12v under both conditions, your dynamo is probably faulty. If the two test conditions are met, then it is probably your voltage regulator that is faulty. You should probably check the condition of the warning light connection as well - it needs to earth properly in its socket before it'll light.

I've kept the generator in my '67 and am happy with it so far.

Hope this helps - let us know when you trace the problem.

Aidan
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1967 131