[en] We analyse (e, 3e) processes on helium, with one fast and two slow electrons in the final channel, where strong deviations from a first-Born description were reported recently (Lahmam-Bennani et al 2001 J. Phys. B: At. Mol. Opt. Phys. 34 3073-87). The four-particle continuum is described in different approximations leading up to a 6C wavefunction which takes all two-body Coulomb interactions into account. It is shown that deviations from a first-Born description arise from two different effects which are important in two different energy regions. (letter to the editor)