Well I seem to have found out what caused the problem and that was injecting a set of morphs and then using an injection file to remove them. That somehow caused the neck morphs to stop working. I checked all of the channel settings but couldn't see anything different from a working V4. I tried to create a full body morph and inject that into a fresh V4 but that also broke the neck morphs on the new V4. So I ended up making a material file for the textures and shaders and very carefully rebuilt the character. I now have a new version of my character that (so far) seems to work fine.

Many thanks for all of the help and suggestions that everyone provided. It is greatly appreciated.

nabob21