Thanks to Jody G. of Conway NH-for the fix. Removed driver side wiper arm only. Removed two covers (broke the fastener-replaced with a drywall molly and screw). Folded back the cowl cover and had complete access to the bent tab. Could see how the stop catch missed the docking part of the bent tab. Used a brass rod (1/2" dia. x 8" long and a hammer to tap the bent tab inward. Replaced all parts and Presto ! Perfect.

Cost $ 0.00 time 1/2 hour. Final comment: Jody u rock ! Thanks a million for your great instructions.

Windshield Wipers suddenly stuck in vertical position! Seems this is another common complaint for Buick! Why doesn't GM fix all these common problems?!

Update from May 3, 2009: Removed windshields wiper arms. Remove cap, unscrew nut and then pull arm straight off--hard to get off. Remove windshield washer tubing. Take out 2 fasteners (pull out --2 pieces). Take off shield. There is another covering over the wiper motor. It is fastened with another pull fastener. You will see motor with black cover. remove cover. There will now be a gold plater device. On the right side you will see a silver park tab. The park tab was bent. Straightened it and added small piece of metal to make it sturdier. Made sure wiper control in off position. Reverse process of putting back together. Make sure wipers are put back on in down position. Fixed by self. No cost. Lots of posts and repair sites suggested buying replacement parts and others stated that they had ongoing problems with this. Park tab is not made out of very strong material.