Evolution of the gain solved by SRoll for four representative bolometers. The left column shows gain as a function of signal level in ADU, with values determined from the data in blue. The red line is the best fit, and the pink area surrounding it is the standard deviation of a four-parameter model of the residual ADC non-linearity fitted to these data. The right column shows gain as a function of pointing period, and shows that the model is able to reproduce the broad features of the remaining gain variation observed during the mission.