what i was in reference to in relation to the windings enamel, is the insulating coating
that appears to have some cracking and corrosion in the pictures, it might be just an artifact of the photo and not as bad or bad at all as it looks in the photos
in any case, i would carefully inspect those windings, and get a small can of glyptal (sp) or its equivalent and brush some on the windings to help seal them up and secure them if any are loose so they don't grind on one another from normal vibration and short.
i think the stuff is called glyptal, whatever it is, check with a motor rewind shop and they can tell you what to use, for that matter take a small jar with a tight fitting lid and see if they will sell you a small quantity.
you mention finding a manual, do you have a link to it?
many years ago we discussed either here or on the microcogen forum the transformer controlled generators, and at the time i found a link to the ST generators that are transformer controlled, but have never seen or hear of one being imported to north america, at least one that ended up in the hands of a forum member.
if that is what you have, and i suspect it is, i think you will be really happy with it once you get it sorted out.
if it were mine i would try to get it working to determine if the thing wasn't internally damaged in some way, such as shorted stator or rotor, and if it checked out ok, i might well take it all apart and replace the bearings and do a thorough cleaning, and may well also send the stator and rotor out to have them vacuum dipped and baked if it looked like the insulation was showing signs that it might be improved upon.
all in all a really nice generator design.
bob g