I had this on my MK2 and it was because the wrong size wipers were put on, as far as I recall the 2 wipers are supposed to be different sizes. I expect some people just measure one and then buy a pair that size. Changing them is a pain though. What I did was turned on the wipers until they get in the pointing up position then turn the ignition off so they stay there.
I've had the wiper trouble on both of my MK1s. Not sure if wiper size is the issue, as it's the body of the wiper (if you know what I mean) that's hitting the metal strip on the side of the windscreen. I've considered sticking little blocks of foam on to the wiper body in order to deaden the "blow", but I haven't got around to it yet.
It's a shame that the "ruthless pursuit of perfection" let something like this slip through the net, becaue it's just the type of thing that one's smart-arsed "friends" are likely to comment negaively on..."Oooh, your wiper's making such a lot of noise, and you're getting how much mpg? Doesn't happen on my Daewoo Crapmobile..."
Apologies to Daewoo owners everywhere, of course... :winky:
djp