my teacher speak: repeat, repeat, until works (aikikai super traditional)
the failure does not necessarily occur with the strongest. The problem: not all resists the same way. some leave movement occurs without resistance.
when there is resistance, I can not keep the body of the uke in the same vein of the arm.
example: if I make ikyo in the the right arm of the uke -> my right hand low his fist, but my left hand can not low the rest of the arm.
if I put my left hand nearest the shoulder, the pressure on him will be stronger?
advised me to stay as close to the body of the uke?
correct mode e my wrong mode (final position):
Main reason is because you don't keep unbalanced your uke all way down. In one moment he recovers his balance, relax (or stiff ) his arm and then you can't manipulate his arm correctly to put him down.
My advice would be using two vector of force at the same time. One that goes through his hips (you create it by pushing with your hips toward his hips) and the second is cutting motion of kesagiri with both of your arms. Both vectors must be applied simultaneously from the moment of first contact and maintained until attacker is down. Additionally, to manipulate his elbow correctly you have you grab it from the bottom, this way your elbow is under his elbow all time and you can push it with your elbow through all technique.
Here you have ikkyo omote:
and ikkyo ura: