My 500 has seen wet snowy extreems, I used to have a 503cw and it also seemed bullet proof as well, although I never used the flash metering chip anyway.
I wouldn't expect the winder to fair well, put the manual crank on and go for it.
I never just let water pour down on it! It's no Nikonos.
@ Ted... My Hasselblad system has been dusty farm combine/harvest operations, hung outside flying aricraft, cathedrals, the most dirty and hot steel mills, coal fired powerplants, welding operations, pig farms, and hiking in the snow, frozen in the car to 10 below, and Cherenkov radiation at a small nuke plamt (that place was clean).
They can do anything (reasonable).Hasselbald used to have this "school" that traveled the country in the early 1990's there was a women that gave a talk, about her photography of yellowstone and rainforests using the Hasselblad she got them more than wet.... I'm a believer in the 500 system by experiance. Go use it sensibly and make some great images.
Fashion a zip-lock bag to protect it. In a word, my 500 /503 and CF lenses have been rained on and snowed on, I bush them off, keep them under my jacket when not on a tripiod or being aimed at something. Yes mine have been wet (sensibility is needed).