Their is not volume knob stl file. https://user-images.githubusercontent.com/35937408/89564013-9c659700-d7d9-11ea-81cf-3661a3b5c776.PNG
Probably best to file an issue on github for this.
I filed one 5 days ago and their has been no response.
that’s not too unusual. Mark1’s not exactly a recent item. Did you check the history of that file to see if it was updated incorrectly?
I do not see the file at all in the changelog.