I just bought a used Tucson Limited, 2011, with 30,000 milles. The Hyundai dealer went out of business the day after my purchase. The car works fine, except when I am on the expressway, going 70 miles per hour or higher, the sun roof has a loud humming sound. Any suggestions on how to fix this? Is it a common problem with this model? Should I buy a wind protector shield? Should I call another dealer for advice?