The attached plot shows a trend of 60 days of beam spot position on the IMC WFS. Excluding two manual re-centerings of the beam (I'm sure about the last one, since I did it) the beam is not moving significantly on the WFS. The peak to peak motion is at most 0.1-0.2 in units of QPD normalized signal, which corresponds to 0.06-0.12 fraction of beam radius.

The position looks quite stable over long periods.