Pulse profile evolution of M15C as observed at Arecibo. The pulsar slowly faded away over the course of about three years, probably due to geodetic precession. The vertical dotted line indicates the central location of the peak as observed until January 2010. The shift in the location of the central peak in the bottom right panel is consistent with a 2.5% phase shift observed in the timing observations (only the relevant ~10% of the pulse phase are shown here). This shift is indicative of an emission component different from the one observed up to 2010 that moved into our line of sight due to geodetic precession (Ridolfi et al., in prep.). There were no observations at Arecibo between MJD 55 202 and MJD 56 409.