This was far harder than it needed to be.. dunno about anyone else, but I found that the screw didn't really fit through the replacement chrome part - the hole was too small. I ruined the head of the small torx driver I bought solely for the purpose while trying to tighten it (I can't remember the size, sorry).
In the end I used some wire cutters to cut the pins off of a couple of long drawing pins and used those instead. They can't fall out because of the battery cover and they do just as good a job at stopping the chrome part sliding out sideways.