When removing the tender body shell you grip onto the two sides where the number four is located, push, and lift up and it should come up. However for some reason my 80s hornby Gordon came with the tender shell glued which I don’t believe is normal but if yours is glued it’s going to be a little more difficult. If for whatever reason your tender shell is glued on, I would just go in with a very small flat head screwdriver and just pry the tender body up and that should work as well.