"Should I just take the generator and take it to the rebuild place to have them test it? "
Yes, but take both the voltage regulator and the starter to the "rebuild place".
When you reinstall the generator and voltage regulator, be sure to repolarize them (
as described in the Shop Manual).
An off-topic, but related, observation:
the Shop Manual says that
some 6v positive ground and 6v negative ground voltage regulators are different.
A recent post said they were the same.
