I just stumbled on this site http://www.societyofrobots.com/actuators_waterproof_servo.shtml
I don’t ave any idea if or how these modifications will work, but there are quite interesting.
P.S. I realize now that I should have posted in the “How To” section … sorry abut that
I have used different things, and there are two schools of thought, one is to make it permanent(epoxy, potting compond, silicon) in the hopes no water will ever get in (tough to do when you need an exit hole).And impossible to clean/ dry if water does get in.
The exception would be a water proof box.
The other is to use oils or greases that leave a film( like corrosion -x,LPS , engine fogging oil, ect… there are abunch) so that you have immediate protection if water gets in ,but you can open up the servo and wash it out.
I like to use a combo of both, first use waterproof epoxy or potting compound to encase the circuit boards, and then use an oil or grease on the other appropriate areas.The best ones I have found are the type that go on liquid and then dry, leaving a thin waterproof coating.
I like fogging oil the best. Its used to preserve outboard engines during winter, it is kind like cosmoline that the military used to use.