Not quite clear where the screw came from, turn signal switches are usually self centering and require you to push in to cancel, you said when you push it to the left the left turn signal doesn't come on, or are you saying when you push it to the right the switch doesn't return to the center postion? Not clear as to what is not working. You also should look at the switch cleaning sticky in the Tech section there is a post there that shows how to clean the turnsignal switch. Give us a little more information and i'm sure someone will be able to help you.
