Thank you Rich1988 - mine is different but I have finally managed to get into it. To do so the bar holding the wheel axles in place needs to be removed by undoing its screws and lifting away. Then the wheel axles need to be lifted clear in order to expose two further screws. Although these screws look as if they are securing the ballast weights in place, in fact they are securing the whole base plate to the tender shell. These two screws are quite short but screw into two long plastic supports which are part of the internal structure of the tender shell reaching from the coal top right down to the balast weights. Hope this helps anyone else with the same problem.

Thanks Rich, but mine is an A4 which has a simple single screw attaching the draw bar to the tender, so the tender on the K4 is different from the A4. There are two screws visible but removing them would release the plate holding the four wheel axles in place. Perhaps I should attach photos when I get the opportunity?

I have a 4-6-2 A4 Pacific 60007 Sir Nigel Gresley Bachmann code 31-954A. I would like to remove the shell of the tender in order to put a sound module in it, but have no idea how the shell should be removed without damage. The exploded parts diagram I have with it gives no clue as what fastenings are in use. Can any anyone help, please.