Today at work...

Today at work I fixed a board by blowing on it.

I'd been trying to figure out what the heck was wrong with it.  I could see no reason why it was failing, but despite all my hours of work I just couldn't pin it down.  I'd swapped parts and tested continuity between at least 100 points.  For some reason I decided that I ought to hit it with some compressed air, and once I did that, it started working!!  Some thing conductive must have shorted some pins.

So there you have it.  When you're working with electronics, inspect and clean up debris as you work.  Keep your work area clean.  And, remember Occam's Razor.