I bought a little mini fridge (ok, it's actually one of those wine cooler thingies) that buzzes loudly.
Took it apart and discovered the source of the problem: a little fan in there, similar to the type you'd find in a desktop computer. Applied some WD-40, bam, problem solved.
However, a few months later and it's buzzing louder than ever. Apparently WD-40 was the wrong oil to use.
[Never put WD-40 in] any electric motor, even if the rotor is stuck from filthy dried-up lubricant! It not only removes any remaining lube, but it can melt coil wires (the lightly-coated copper wires twisted up in electric motors) and cause an electrical short. New fan motor!
What can I do this time around to keep it lubricated and quiet?