Here's Steve's notice of the upgraded PCB.
https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1343961059Here is a link to an explanation of the "artificial centre tap".
http://www.valvewizard.co.uk/heater.htmlIf the Edcor's heater outputs were center tapped, the center tap wire would go to ground. But since it is not center tapped, the TWO 100 ohm 1/2 watt resistors act as a center tap to ground.
I happen to have two extras that I'd be glad to mail to you. It's a bummer that the BOM hasn't been upgraded to include the two resistors. PM me your address if you want them.
Mike