Mild bathroom cleaner i.e. regular Flash or Mr Muscle, followed by Peek Polish has worked well in the past for me. An old toothbrush works well for scrubbingI find that an overnight soak in Barbicide usually does the trick for me. However, I've only used it once on an aluminium handled Rocket 500 because it stained the handle.
Does anyone know a safe way of cleaning up aluminium handles razors?