I have recently acquired a number of (presumed) Bv. 107 transformers, and am hoping to establish their authenticity. While the bobbins, spool labels, and foil tab appear accurate, there are irregularities in the group. There are two transformers with significant discoloration of the laminations, which has a gold coloration under light. The rest of the transformers do not share this degree of oxidation. To follow this point, the transformers are unpotted and I'm unsure whether that is consistent with factory spec. Any help addressing these curiosities, as well as any winding info not subject to "trade secrets," would be greatly appreciated. Thank you.