Hello Dave,
I got the gas filler valves from Dave Mees of Abbeybach Engineering - http://www.abbeybach.co.uk/index.htm
He gets them direct from Graham Langer at Accucraft UK. They are also stocked by Anything Narrow Gauge - https://anythingnarrowgauge.co.uk/16mm-accessories/z13gas-filler-valve
I'm surprised that Accucraft USA are still selling the previous faulty valve, but maybe they have not updated the image they use. A fellow modeller had that problem when he ordered a goodall valve for an Accucraft UK loco that I had recommended - he got a different version to the one I received (mine was as the image they were using).
Chris Cairns
Thanks! I have a new gas can adapter from Forest Classics (along with a Mamod SR/TE Bix burner set!) coming today. If that doesn't work out, a new valve is next.