Our '05 Golf TDI just passed 110k and I was asked to look at it by the driver. Seems to be having a few separate issues, but there was some rattling sounds coming from the engine bay along with squealing on the power steering which both seem to only happen on the driveway (according to the driver).
I took a look at it with the engine running and the tensioner bounces quite violently. The belt doesn't feel all that tight to me but I cannot really measure that other than by feeling. Here is a video I found on youtube that shows another wobbly tensioner:
Our seems to wobble a bit more than shown in the video with the AC off, and with AC on it wobbles perhaps 2 or even 3x as much. The belt itself is brand new, I just replaced it 5000 miles ago. I don't recall the guides specifically mentioned replacing the serp belt tensioner (I did replace the timing belt tensioner), but maybe I should have.
Could the belt slipping be causing a squeeling in the power steering? Or what could that otherwise be?