I do agree with Carroll regarding much of his diagnosis, but on note 2, the
real reason to replace the power supply is not electrocution, but, what is
your time worth.  Finding a suitable replacement fan, disassembly.
Installation, and reassembly and not knowing if the power supply you just
repaired was ever worth it, or damaged due to overheating.
Power supply = $25 -- $50.
PS  Electrocution is very unlikely unless you don't unplug what you're
working on.

2. Power supply fans fail, too. Unless you are a skilled technician, DO
NOT attempt to fix one, just replace the whole power supply. It doesn't
matter all that much whether it's on or off, there can be a lethal
amount of electrical energy stored inside that box, and it can kill you.
Bite the bullet, and spend the bucks.

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