Janet, you caught it exactly. NOT where we want their center "to go" but spiraling in and ON their center. Play with it. I think you'll find some neat-O toys in that thought, as uke's posture ends up being destroyed usually quicker than by the leading them out, or moving them around, etc. I like it when I can place a hand and immediately feel the uke's posture beginning to crumble.

And the other thing, it's not painful to uke. Very difficult to deal with from uke's perspective, but it's not a pain-compliance thing at all.

Howard got me to thinking about this by saying his thing about the "ball in the gut" thing he uses to explain his Daito-ryu principles, which are different in expression, if not result, from the Tomiki stuff I do - the thing about one side moving out towards uke while the other side moves back in, yin-yang etc.

I stuck that with something my original instructor, Ray, always was saying about the arms being "gratuitous attachments to the center and irrelevant to the actual action of the body/center," with spiral motions which came (to me, anyway) from Hapkido (and you can look up where they got it from), and my own insight about postural destruction centered generally around spine locks and specifically around the l5-S1 joint at the top of the pelvic girdle's shelf.

Without going into a dissertation (probably too late), I've noticed that many folks seem to look at the body as either a solid thing which can perambulate on stilts, or a fluid thing which can go any which way all the time, and IMO both of these are a bit off. To me, the opponent is a ball (the center of mass) which has two independent flat shelves from the ends of which protrude levers with which I can manipulate that center's motion. Most high-level folks get this. The thing that I think most people miss is that the center is never actually in the body's center (well, I supposed squatting positions, such as Jigotai defensive posture from Judo move the CG down into a more geometric position, but I'm not worried about that guy. Defensive judo is just that, defensive and it's not a threat to me. That guy stands up still attached to me, THEN he's a threat, but enough on that).

People standing up, either square, or in a more combat ready position (one side slightly leading, whether your art favors straight-on or side-turned, whatever), if you can get that big ball in the middle to roll enough to tilt the bottom shelf (i.e. flexion of the L5-S1 joint) and they suddenly lost most of their stability and strength.

I'm going off track so let me yank myself back on topic.... witht he above very brief description of the body-concept in mind try this very basic drill. It's partner training, so steer clear until you are cleared but this isn't in any dynamic or slam-bang, it's just the opposite... exploratory. Once you get it, you can start using it at the instant of contact with the opponent, it's very neat.