There was quite a bit of water coming in through the cable and trickling down the main bus and through the breakers to the bottom of the panel and dripping to the floor below.There were no signs of rust or corrosion in the panel or breakers.So I...
1) Sealed all possible points of water entry...SE cable weatherhead,meter socket, etc
2) Pulled meter to kill power, then removed every breaker and wiped and dried all signs of water off the main breaker, panel bus and breakers.
3) Replaced breakers at top that had excessive exposure to water.
I will visit the home at the next heavy rain to see if water is still getting in. There wasn't a need for complete replacement of the panel in this case, IMO.
In the past I have replaced panels beyond repair from water damage.
NEMA has information at this site on what they recommend for water damaged equipment... http://www.nema.org/papers/waterdam.html
Thanx for the feedback...