If you look at the point where the wiper pivots on, the cover will come off, and under it is a nut. If you remove that nut the wiper arm will come off. If you look at the now exposed drive shaft for that wiper, it should taper out, with little ribs perpendicular to the threads. Also if you look in the hole to the wiper arm, there should be ribs made to mate with the ones on the shaft. You should be able to properly align the wiper arm, and give it a good tightening, any you'll be good to go. Un-fortunately thoose little ribs can get worn slick, which is probably the case on your car. If they're still there on the shaft, you can just go down to your favourite junkyard and pick up a new arm. If they're worn down on the shaft, then the problems get bigger. In thoose cars it's a bitch to get to all the wiper linkage under the dash to replace it. Additionally it's kind of a mechanical wonder, so not only is the workspace cramped, but the way things go together is somewhat tricky. I don't have much advice beyond this point. Somone totaled my car the day after I put a good whack in trying to fix this problem, so I never had to deal with resloving it.

-Good Luck
Eric Reinecke
ibis@mac.com