From left to right: grayscale representation of the CLEANed periodograms as a function of velocity of He ii λ4686 spectra for the 1989, 2012, and 2013 datasets. For the layout see Fig. 2. Vertical dashed lines in the main panels are drawn at ± vsini. For the full profiles see Fig. 3. The tickmark at ν₁ = 1.315 d^-1 indicates the frequency with the strongest power in this line in August 2013 (see RH15), which is absent in our three datasets. The tickmarks at ν₂ = 0.245 d^-1 (=4.1 d, our adopted rotation period) and ν₃ = 0.495 d^-1 indicate the frequencies found in Hα in August 2013 by RH15. The dominant frequencies at ν₀ in the Si iv in 1989 and at ν₄ = 0.642 d^-1 (1.56 d) are drawn at the peaks of the 1989 and 2013 dataset, respectively. The dominant peak in 2012 is at ν₅ = 0.741 d^-1 (1.35 d). The tickmark at ν_H = 1.5808 d^-1 (=0.6326 d) denotes the periodicity derived from the Hipparcos lightcurve by Marchenko et al. (1998), which is remarkably present in 2012. The indicated frequency ν₆ = 2.386 d^-1 is absent in this line, but present in nearly all other helium lines in 2013, see Table 5.