Re: Tohei, Solo Practice, and Internal Training
I first started in Ki Aikido after reading "Ki in Everyday Life" in the mid 80's when in Italy. Didn't practice there for more than 9 months or so, but with a very nice group in Turin (can't remember names any more). Most of my training since then has been Aikikai related - in the Yamaguchi lineage.
I find that "keep weight underside" works well particularly when teaching sword work and how to cut/drop a sword. Also related to the Sayu exercise noted above, and variations such as lifting the arm up while still keeping the shoulder down - same for lifting a sword.