I had this happen to my S80. Took the door latch out of the door and took it apart. There is a small plastic gear that meshes with a worm screw. The plastic gear was broken allowing the shaft to slip and make the buzzing noise. I went to my local pick a part and got one and replaced it...no more noise anymore. You have to drill out a pop rivet to release the lower section of the window guide to get the latch out. When you put it back in, I attached mine with a nut plate and screw then ran the window up and down a couple of times to be sure everything was lined up correctly. I do not recommend the you unplug the drivers door module. The cable is long enough to just rest the door panel out of the way. Good Luck