Garage Wall crack


I have a crack in my concrete block garage wall .It starts where Brickie when building the wall 20 years ago fitted a vent in the line of second block from the top.The block above the vent was left without real support at one end and has dropped a bit and from that end of the vent aperture there is a zigzag crack down the wall to the floor.When I first noticed the crack appear I cut a brick to size and placed it in the aperture to support the dropped block and cemented up the crack.This seemed ok for some time but now I notice that the crack has opened again.
I hope I have been clear enough with my problem explanation and are there any suggestions on how to put things right.By the way the concrete floor is ok.
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On Wed, 26 Sep 2007 20:54:50 +0100, a particular chimpanzee, "allan"

The hole isn't the cause of the crack. It would simply be a 'weak point' in the wall (or rather, where the stresses are highest). If the crack continues to the floor, there is something wrong with the foundations.
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Hugo Nebula
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randomly hit the keyboard and produced:

Thanks Hugo
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