I have an additional point that might be worth checking. Half a year ago the right side window fluttered more and more on the A column. I wondered because nothing was bent or anything else was wrong. It was suddenly different. Then I noticed that the window was shaking a bit when I opened the door. Then I saw that two of the three screws of the mounting part with the knurled nut where the disc is inserted in front in driving direction had come loose. This is not noticeable when the door is closed and the window has contact pressure. I tightened the screws carefully (into the wood) and the side window had a perfect fit again without fluttering. Tighten these screws only when the side window is removed.
