I have owned my 179 Cx Custom for almost a month and am enjoying the bike. I still need to fix trip meter and ignition switch won't turn bike off , so I use the kill switch. Just recently i have noticed a buzzy vibrating sound when I apply my rear brake....instead of the squeal you can hear from a car's disc brakes this is a louder deeper sound. Kind of hard to explain but the sound is quite noticeable. I don't have any knowledge or experience with drum brakes.....obviously they need servicing....is this a serious issue in terms of safety. Thanks for your help in advance.