Sebert Motors is showing that they have made brake drums for the Arnolt. Unless you are wanting strictly original parts I would check these out.
Sebert Motor Car Company- Brake Drums
I can't remember who all the Arnolt owners are by their forum names, but we are trying to keep up with the owners and their cars. I would appreciate if you would contact me by email with your ownership information
regards,
John (john.simmons456@gmail.com)