Loose two post

This is how I tightened my two post mirror head. After pushing in on the glass I removed the locking ring and then removed the glass and spring. I then used a pair on my welding vice grips as shown in the pics to compress the black plate on either side of the ball. Worked like a charm. I didn’t protect the chrome with anything and I didn’t damage the outer body but I would suggest some painters tape to both protect the chrome and prevent slipping although I had no issues.