"While there are countless sources of advice and marketing tricks on how to sell ebooks and books online on Amazon, the most important factors of all are to have a good product and to attract positive attention to your books.
If you have published more than a couple of titles, perhaps it has been some time since you analysed what you are really doing to attract attention."
I do have to note that the advice to post on Google + is old - Google + is sadly no more.
I did recover and change the description to my book (Deliveryman: Palm Springs), and though I think both of those areas are much improved, it hasn't resulted in any movement. I haven't advertised it though, so the experiment continues.