Fiber Connectivity Problems: Check Each Strand With Light

I got a call from a customer that was having fiber problems between floors of a building the other day.  He was out of town and asked me to go take a look into it.  GBICs looked good when you looped them back on each side of the Brocades, so the problem had to be the fiber.  I got the director to shine his phone flashlight (which is a cool tool these days) through the fiber strands and this is what I found in the below picture.  So I rearranged to the good strands and all was working again.  Im not sure what happened before I got onsite, but I do know that they share a closet with another company.  Who knows, but Im glad they are back to good.