So does anybody know any good exercises to develop contact/power?
the best advice you got is above - visualize. you got the comment on being in the moment and using your brain; also excellent advice.
use your heart: how do you feel? how does uke feel?
know yourself so well, that you become aware of uke as though you shared the same body.
i have heard others tell, and myself experienced 'losing' the knowledge of attack ending and
technique beginning. i really think this is the goal, and what the masters mean by 'connection'.
i don't think it's esoteric. i think it's life uncloaked.