I just fixed my tumbler that had the problem shown in the above video, at 140k miles. Vibration technique with the air tool would not work. Rather than pull the steering column or call a locksmith, I used channel lock pliers to break the plastic part off the tumbler which surrounds the key when the key is properly inserted. Removing the key, and putting it back in, was not the problem, but the tumbler refused to turn like it should when key was inserted. Had to break off the plastic piece off the tumbler and also part of the associated tumbler metal in order to see the channel where that little locking piece sits, which locks the tumbler in place (not letting it turn) when the key is not inserted. My tumbler was worn out and the vehicle key would not lift that stop piece up out of the way so the vehicle key could turn the tumbler. That little stop piece is like the flywheel key on a small engine which holds the flywheel in its proper place in relation to the crankshaft (a flywheel key). Once able to see into the channel (like a flywheel key channel), I was able to insert a makeshift tool from a computer repair tool kit (anything that would fit into that channel might work, just keep trying) and I was able to use it and see it manipulate that stop key. I kept messing with it, turning the vehicle key back and forth in the tumbler and finally was able to get that stop piece to lift out of its channel enough that it released and the tumbler was able to turn toward the start position. After getting it into the start position, I inserted a probe into the hole on the top of the tumbler housing and, as it should, out popped that worn out bastard part that is usually called the key lock cylinder. From now on, I will replace that problem part at least every 100K miles, and maybe more often like 50K if I can afford it. This was easily one of the most frustrating repair jobs I have ever encountered on the '06 Blazer. Cost me just $42.00 on Amazon for a new tumbler and key.
...Mike.