That is different from mine which are cast in Mazic. Perhaps Bosch had better thoughts... I wonder then how many people have the mazic ones and how many the brass ones.
I'll have a look at the one on my car, as it wasn't charging much and it's time the brushes were cleaned (or freed!) Last time I rebuilt it was quite a few years ago in the hotel carpark in Varallo, when it stopped charging altogether.
Regards, John