The driver side windsheild wiper cleans off 2/3 of

I have 95 and 97 '850s and both of them have the drivers-side wiper problem. One fix is to but 1/2 of a washer under the arm when it is tightened down. This will tilt the arm and correct the problem. The other is to gently bend down the aluminum arm when the wiper is stopped at the fully left position. (turn off the key when wiper at that position)

Try this http://volvospeed.com/wiperarm.php

Have you checked the wiper "arm"? Possible that the spring in it has become weak, making it not fully press the wiper blade against windshield.