A rolling x-stroke might be the key for that. Take my advice and don't try to correct it...just trust me on that one :p
There is a section in the Wiki about the rolling x-stroke and I believe there is a nice little animation for it as well. I would suggest putting a layer of tape on it to avoid uneven spine wear while learning that stroke.
Anything else I can do to help, just shoot me a PM. Glad to help out!