The vast majority of clocks fail due to lack of lubrication or the failure of an aged part.
Recently I had the opportunity to repair several clocks that were damaged in the Katrina hurricane.  Shown here is an English industrial fusee that operated a time recorder or other device long gone before the hurricane damage.  The clock was the typical overbuild seen in English fusee mechanisms.  I was very surprised at the damage done in the short time the movement was in the salt water.

The corrosion was substantial.  The blued hands were deeply pitted as were all the steel screws.  The pinion leaves also were pitted.   The most serious damage was to the pivots which were so deeply pitted that several had to be replaced and the others had to be reduced and the plates bushed to fit. Even the brass was pitted.
  I am not used to seeing such extensive damage knowing it occurred with only a few days in the saltwater environment.