I understand what you mean, however I believe there maybe an issue with your uke's. I'm not sure what rank you are but if you are in the higher kyu ranks then perhaps you do need to seek a solution to the problem. However if you are a lower kyu rank then perhaps your uke's should only be providing enough resistance to let you push through with the correct shape and form. I don't believe they should be blocking you off, otherwise you'll never learn the correct form and shape.
If you are a higher kyu rank then your uke's should be gripping on for dear life, and here are my humble suggestions to solve your problems.
One method is to close your eyes and think "happy" thoughts, in the meantime you must do the entire technique from start to finish in one movement without stopping. If you stop in the middle of your technique it gives the uke a chance to rebalance and become strong again. Also whilst this is happening you must be breathing out through out the entire technique. So, close your eyes breathe out and do the technique without stopping.
The other method is to try and become the complete opposite. That is do teh technique completely relaxed. This means you should be limp, so if you smack your muscles they should wobble around. To help this along, in particular with morote dori kokyu ho you can flap your hands up and down (from the wrist) as you move through the technique (like you are waving to someone).
But most importantly it is important to know the difference between Ki-ing up and tensing up. You cannot possibly do any techniques if u are as stiff as a board. You should also remember that techniques should be non confrontational so if you do encounter resistence then perhaps the answer lies in using a different angle or using more kokyu.
Well I hope my humble suggestions help, and I haven't taken up too much of your time by crapping on for too long. Good luck with your Aikido