I took my Beauchat VS-10 into the local dealer for it's
annual servicing the other day and got a surprising
phone call from the service tech, asking me to come
by so he could show me something.
Now before I go on, I want to state that I take very
good care of my equipment; my life literally depends on it.
I rinse everything in fresh water, and make sure that
the rubber cap is always secure on the inlet port when
the regulator is not in use.
Well, when I got to the store, I was shown my regulator
first stage completely disassembled on the bench, and
the sight was profoundly shocking...there were truly massive
encrustations of salt crystals in virtually every area
of the interior cavity, and thick green grungy stuff all over
the inside brass surfaces in both the high pressure and
low pressure regions.  The VS-10 is balanced-diaphragm
type first stage, so the only way sea water could get in
is through a rupture in the bias diaphragm or through
the inlet port or a bad o-ring somewhere.
  This first stage has never had an air leak, which would
indicate a failed seal or o-ring, so the water has to have gotten in
past the dust cap, probably during rinsing in the dunk tanks
at the Galapago Inn, which was the last place I rinsed my gear
by immersing it completely (I always squirt it off with a hose
here at home).
The point of this message is that my regulator was on the
verge of a serious failure, although I believe I take
better than average care of my gear.  Don't let yourself get
caught in a situation like this.
1. Never skip the annual servicing, even if you are only an
"occasional" diver.  If any water has gotten into that first
stage, it will cause corrosion and eventual failure if left
uncleaned.
2. Whenever the regulator is dismounted from a scuba cylinder
and de-pressurized, blow out the dust cap with air from the tank
you are removing the regulator from, and install the dust cap
immediately.  Regularly inspect the dust cap for cracks and missing
o-ring.
3. Avoid dunking a regulator first stage when it is not pressurized,
rinse it carefully with a hose, taking care to not blast water under
the dust cap
4. Don't use air fill stations of questionable or dubious quality,
a tank full of contaminated air can damage your lungs, not to
mention your regulator.
5. When mounting a regulator to a tank, check to make sure that
both the tank valve outlet and reg inlet are clean and dry, as
any water or other contaminents will be blown right into the regulator
innards as soon as you crack the tank valve.
6. Keep an eye on charter boat crews. Most of these personnel will
handle your equipment as carefully as you do yourself, but 
occasionally there are inexperienced or trainee deckhands who may not
be completely familiar with accepted ways of handling a regulator
so as to keep water out of it.
Stay wet and have fun!
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