[Pamphonica]

Hi John,
How very interesting. I suspect still that mine has had a mains transformer transplant.
But comparison of all these variants is instructive.
Your chassis is the same colour and the same deeper profile as mine.
And the two grommets for the original transformer wires are like yours.
However, the underside of mine does not have the lovely neat grounding layout yours has so some delving is in order.
I wonder if the previous owner of mine has any information. (Please PM me if you are that previous owner! Anonymity guaranteed... )

Jeremy