Thanks Paul. That's nudged me a little further along the learning curve. I can see from the event dump that the Event Cntrl 65955 (Fuel_Selector_Off) is the mode when I start the flight cold and dark. If I use the mouse to switch on the fuel (currently my only option), I note from the log that the Event Cntrl 65956 (Fuel_Selector_All) is now present. I've tried using Buttons & Switches - select for FS Control for Fuel_Selector_All, both from the pull down and by entering it as a Custom Control 65956. I've tried a Parameter of '0' and '1', but the assigned switch still doesn't work.
Is there something I'm not understanding here, or could it just be that this aircraft doesn't support this type of assignment/command? Thanks for your help and advice.
Bob