You are not the only one who has had this problem, I am sending you the GM technical service bulletin that covers the repair for it.
Some customers may comment that the windshield wipers park in the outwipe (vertical) position.
This condition may be caused by a bent park tab on the windshield wiper motor bracket.
To correct this condition, install a new windshield wiper motor crank arm and a windshield wiper motor bracket service kit. Use the following service procedure:
Arm, Windshield Wiper Motor Crank
Windshield Wiper Motor Bracket Service Kit
Parts are expected to be available from GMSPO on 6/3/02.