Retired Engineer

There was an engineer who had an exceptional gift for fixing all things
mechanical. After serving his company loyally for over 30 years, he happily
retired.
A few years later the company contacted him regarding a seemingly impossible
problem they were having with one of their multi-million dollar machines. They
had tried everything and everyone else to get the machine fixed, but to no
avail. In desperation, they called on the retired engineer who had solved so
many of their problems in the past.
The engineer reluctantly took the challenge. He spent a day studying the huge
machine. At the end of the day, he marked a small "x" in chalk on a particular
component of the machine and proudly stated, "This is where your problem is."
The part was replaced and the machine worked perfectly again. The company
received a bill for $50,000 from the engineer for his service. They demanded an
itemized accounting of his charges.
The engineer responded briefly:
One chalk mark: $1
Knowing where to put it: $49,999
It was paid in full and the engineer retired again in peace.