Yes, the washer under the nut is the trick for fixing the wipers.I used a
piece of aluminium foil, wrapped around the shaft, and then put the arm
back on.Then the washer and nut.

If you want to repalace everything,not too bad.Remove everything at one
time is best. Remove the glove box.The 4 bolts on the dash board hold the
wiper moter on.Getting the wires unhooked,and routing the new ones  was a
pain for me.

Go to a junk yard and practice till perfect(1 time).Check the wiper arms to
see that they are tight ,first.Use this junkyard part for your van.Moter,
and transmission assembely(thats what they call it).Check in the secret
storage box under the drivers seat for treasure while you are at the
junkyard.I get half. All wiper motors fit all vanagons 80-91.