  The efficiency statistics of a small thermodynamic machine has been recently
investigated assuming that the total dissipation was a linear combination of
two currents: the input and output currents. Here, we relax this standard
assumption and reconsider the question of the efficiency fluctuations for a
machine involving three different processes, first in full generality and
second for two different examples. Since the third process may not be
measurable and/or may decrease the machine efficiency, our motivation is to
study the effect of unknown losses in small machines.
