Re: Practical internal training ?
For me at least, the interesting question about all this concerns O Sensei, Tohei and Kisshomaru.
If you look at some footage of Kisshomaru (on for example the aikidojournal postwar greats DVD) there's a scene where he is demonstrating funakogi undo, watching his father do the same exercise with Terry Dobson (in his endearingly short 'foreigner can't get the right sized' hakama) it's quite obvious that O Sensei is using his centre a LOT more and is displaying quite openly some of those 'internal skills'. Kisshomaru however looks like his just copying the motion and isn't using his centre.
Tohei Sensei doing the same exercise appears to most definitely be using his centre quite strongly. However we know that while he was a careful observer of O Sensei, his 'internal skills' came mostly from the Tempukai and some Bell misogi. Tohei's aikido wasn't the same as O Sensei's (I can give some good examples I think of techniques that look to me as though Tohei is trying to throw people like O Sensei, using similar kuzushi but in a different way with different connection to uke).
Tohei started training in 1939 was drafted not long after this. When people say O Sensei wasn't teaching internal skills after the war (or that he was but nobody noticed what he was doing), does this put a date of 1939 on the 'decline' in this actively taught aspect of O Sensei's aikido? Certainly Kisshomaru didn't begin taking an active interest in aikido until the late 1940s early 1950s from what I understand. So that would work out chronologically at least.
One thing that interests me is that the misogi Tohei did at the Ichikukai (spelling?) basically seemed to involve making one so physically exhausted that you had no choice but to do the technique in a coordinated 'internal' way with relaxed power. Your muscles simply wouldn't listen to you otherwise. I can recall my teacher seeing one of my sempai being too physical during randori practice, his solution was to make my sempai do a handstand against a wall and from that position do 20 pressups, after this of course the guy couldn't use his arms properly and so his kokyunage improved.
Could it possible be that the internal skills displayed by the prewar uchideshi such as Tomiki simply be due to the severity of the training at 'Hell's Dojo'? I recall hearing a story of one deshi in the Kobukan being able to push an iron nail into a lump of wood using only his thumb. Could that be it or a part of it? Could it be that Ueshiba never actually explicitly taught internal skills at all but they were fostered by the severity of the early Kobukan training environment? Perhaps aided by hints and tips and the careful observation of his students?