Enjoy the brush!
Your brush is really adorable, enjoy it. Try to contact again the seller and ask him to change the travel tube with a large one or get the Muhle travel tube which is made of plastic and it is also adjustable. In EU costs 3,20 €. Next time you want to buy a brush, have a look in this site. Razors & Shaving Brushes - Diamond Edge
Great prices and very good service.