First off, I want to point out that these are not block avoidance techniques. There are block modification techniques. Meaning you only use them when encounter a word you're unable to say or you're blocking on it. Also you still say the block word sound / word fully. You transition from the 'mmmm' or 'aaaah' or 'nnnnn' or 'ng' sound smoothly into block word, making sure to keep the vibration in your lips going during the whole transition. These initial sounds which are added are also supposed to be very soft hums or intonations depending on the sound used, almost barely audible while the blocked word is gradually turned on from low to loud volume. And before you start the technique you have to make sure to have enough breath support for the sound, so you should also take enough breathe in through your nose before starting the technique. Steelspy, chances are you that you were blocking on the 'mmmm' sound because you were already out of breathe. Some blocks are just due to poor breathe support. And instead of switching from 'mmmm' sound to 'ummmm' sound, should you try and first figure out which you're blocking on the 'mmmm' sound, are you using too much tension in the lips?