[Zope] External Method reloading

Is there some magic incantation I can call that will cause all my External Methods to reload themselves? I have a number of External Methods that act as factories for classes defined externally, all of which are subclassed from a single base class, and when I change this base class I have to reload each method separately, which is irritating. Does anyone know a workaround for this? David Loeffler University of Bristol