1) Have you tried different versions of NeoGamma? e.g NeoGamma R6 or Neogamma R7. Try using different cIOS249 revisions. E.g cIOS38-rev13b, cIOS38-rev14.
2)Since one of the steps in the make your wii a virgin guide is to update, it is currently not advised to do it since the latest update is 4.2, if you want to remove your cIOS, re-running the installer can do so and AnyTitleDeleter can help you as well if you're careful.