After feeling quite frustrated with ikkyo in my last practice, it was great to read these comments. Rather than feeling smoother and more relaxed the more I practice it, I notice all the things I am doing wrong. So this is shakey advice. But, it did seem to help when I unbalanced uke early, using a soft circular block (already mentiond) of his shomen-uchi to bring his hand to my center and his balance forward. Without the early imbalance the technique required to get the levers turning the right way seemed pickier, more dependent on precise timing, but taking balance early seemed to help. It made sense to me to harmonize with uke's desire to pull back after being unbalanced forward, but I confess 100% frustration with attempting to put that sense to use.
As someone already mentioned, getting to the takedown with uke's hand low and shoulder high seemed wrong. When I got the shoulder torqued around and on the way down, with the hand higher, there wasn't much he could do, stiff or not.