I've cleaned the dust out of my computers many times over the years without a problem. This episode turned out quite differently. When I turned it on, my monitor displayed only jibberish.
The first time, I got parallel vertical bands of various colors in patterns, plus some random video noice in the background. I shut it down and reopened the cast, checked for loose connections, and reassembled it. This time, the vertical bands were still there, but with different colors. Also my machine sounded unusually loud—as if all three fans were running at full speed simultaneously. I shut it down and went to another computer to ask you good people for some ideas.
My tools were canned air, a soft brush made for the purpose, and some light use of a vacuum cleaner. By the way, I checked the pins on the VGA connector—no bent pins or other damage.