11-22-15: Lewm
That's lovely, for someone with a Mk2 or 2A. I am loving my Mk3, however, now with Krebs modification. Was listening to it all day today. Incidentally, if the OP is still alive and still cares, it is not out of the question that Richard Krebs might know who or how to build a Mk3 supply complete with servo circuits.
Lewm,
The OP would be advised to contact Bill Thalman. Richardkrebs has used Bill Thalman to repair his own power supply on occasions.