Thanks WT Sharpe - that's a fair point, but the kindle format (for me at least) makes it a pain to get images right. They are easy enough to add, but getting them looking right on the device is a pain.
I probably need to look at an update and get some images sorted. That said, the books are written to be read alongside regular tutor books and I do make chord sheets available on my website for free.
Thanks for the feedback.