if it only does it when its raining its cos youre getting water on the belt.there should be a black plastic guard that bolts on to the inner wing cover which stops water getting on the belt.check the belt to make sure its not worn or loose.when i did my previouse engine change i never got round to putting the guard back what with all the problems and if rained it was a nightmare the steering would go al stiff and juddery when going round corners maily right hand corners i think cos the belt was taking a direct hit.as thwe wheel turns as youre turning right the water spray of the back of the tyre is fired up into the arch and down onto the belt.
makes sense
it certainly made it interesting when i pulled into a carpark with a wall either side of the enterance and it went all stiff just as i turned in, just managed to go back to normal before i was about to plough a wall down!ÂÂÂ
PAS you women
(at least i don't think i have PAS.... 
)
You probably do have it and havent really noticed, its not exactly light.
my mark 2 power steering is lighter than my dads mark 3, which i thought was odd, must of had a new pump at some point
