I could be a bad voltage regulator also.
I've never measured an eton stator AC output voltage, so I can't tell you what is normal or not. Have you tried emailing www.anythingATV.com
through their web site? They have a tech support area, maybe they will respond.
Do your two eton quads use the same regulator? Maybe you can swap them briefly to see if the problem moves from one quad to the other.