The resonant three-wave interactions in an infinite homogeneous magnetized plasma are re-examined using the improved hierarchy presented in part 1. An equation for the wave energy is obtained which, for a spectrum made up entirely of marginally stable waves, is shown to be a second-order Markoffian differential equation, rather than a first-order equation as obtained by others. The conditions under which a first-order equation is derived are examined and discussed. For a spectrum composed of waves with small growth, rates, it is shown that the equation for the plasmon density always has a stationary solution, thus eliminating the occurrence of an ‘explosive instability’ in such systems.