I decided I wanted to get a "proper" sprocket on the back - also with less teeth!! 42T was hurting my fuel economy big time after a 38T original - but now I have a 37T Honda (made in Japan) sprocket on.
Took a photo of the offending sprocket after the change (sitting on top of the bag the new one came in showing it was genuine Honda!).
The scratched paint was not a thrown chain, but rather caused when the chain was removed.