Always looking for something new to read. I'll put it on my list. And I always try my best to have an open mind.
I'm sure that as I progress in my aikido this concept will become more clear to me.
I think the chances of you finding internal power to any appreciable level in aikido are slim to none. Personally, I have never met anyone in Aikido with internal power /aiki. Nor have I seen a video of any teacher- Japanese or otherwise -who exhibited much. I would love to hear of someone, somewhere who does-particularly if they have a video out I haven't already seen.
I would consider looking for those teachers in Aikido who's current training is specifically focusing on IT. In time they will be the best (if not the only) bet on getting IT in aikido.
Good luck in your search.