The cause of a vibration and the source of the buzzing may be far apart and not directly related. Any vibration can make a loose panel or component vibrate against another component or its mount, causing a buzzing or squeaking sound. The rubbing potions are often hard to find, and cannot be seen until they actually wear into the paint or each other. A thorough inspection and a check that all fasteners are tight can sometimes track things down. Good luck in your quest.