This paper carries out an analytical stability study on the solutions of externally excited, symmetrical rotor/stator systems with full annular rubs. The obtained analytical stability conditions contribute to a better understanding of the dynamical jump phenomena, which correspond to the occurrence of the saddle-node bifurcation of the full annular rub solutions, and the transition between full annular rubs and partial rubs, which corresponds to the Hopf bifurcation. A systematic investigation of the influence of the system parameters on these phenomena is performed. It is also found by means of numerical simulations that the Hopf bifurcation boundaries of the full annular rub solutions can serve as good approximations or conservative boundaries for the dry whip instability of the considered rotor system.