I remeber working in marine electroincs and we got a unit in that was broke and we opened it up and found inside a board that was one of the first ones to come out about three years previous in a unit about 2 months old.

Turned out the bloke had swapped over boards with someone to get a new unit.
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P.Allison fixer of big engines Mk2+Mk2a signed by God / Hacked by the Lord Aberdeen Scotland