Quoting Barkalarr: Obviously, I can measure and drill the same holes as the old part into the new part, but it means I need to drill through the leather and the aluminium.... I'm a bit concerned the leather is going to tear, but I'm sure I can get round this.If you're worried about the drill twisting the leather you can make a hole with an awl, a punch or a soldering iron. Is there a hidden bit on which you can practise?
Jonathan