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There is a GM bulletin concerning your issue, The crank arm may also have been damaged from the Ice and snow. Both get replaced under this bulletin.
#02-08-43-002: Windshield Wipers Park in Outwipe Position (Install Wiper Motor Crank Arm and Wiper Motor Bracket Service Kit) - (May 22, 2002)
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.