This paper shows examples of the long term variation (1987-2001) at H alpha and He 6678 including an episode where the disc was completely lost in 1988 and cyclic changes with periods 0.6-2 yrs
https://www.aanda.org/articles/aa/abs/2001/47/aa1796/aa1796.html
The variability that Kevin highlighted (and confirmed in the other spectra) shows small scale variations in the line profiles at much shorter timescales though
Robin