Examples of glitches 28 (left) and 51 (right) without a detected exponential recovery. From top to bottom: Phase residuals relative to Model 1, with the residuals (blue curve) of the most likely exponential recovery model (Model 2 relative to Model 1), corresponding here to zero, superimposed; phase residuals relative to Model 2; frequency residuals relative to Eq. 1 fitted to TOAs up to the glitch epoch, with the post-glitch data all lowered by a certain amount (the mean post-glitch frequency residual) for better visualisation; and $\dot{\nu }$ evolution with Model 2, when used as the favoured model, shown as the blue curve.