The feedback mechanism presented in the paper published by Dwyer (2003) is examined in the context of runaway breakdown and thunderstorm electrical conditions. A detailed comparison between previous kinetic and Monte Carlo simulations performed by the authors and others and those of Dwyer are presented. The role of positrons and bremsstrahlung photons in contributing to the runaway avalanche rate is discussed. An alternative and simplified treatment of the feedback mechanism is presented. Our preliminary results are in basic agreement with Dwyer and indicate that positron feedback is more important. In addition, we find that there is a temporal 'stepping' effect associated with the feedback process and that this effect could also lead to a spatial stepping reminiscent of stepped leaders.