Sadly the Star, the part that often breaks, is not available separately from the barrel and the rest of the assembly, and is sold for an astonishing, you have to be seated because it is unbelievable, price over $1,000.
1. Search on eBay, but they too will be $$$
2. Attempt a repair using modeling putty or bondo, and painting it. It will be about the best you can do.