I also own a e450 with the driver side mirror wobbly as you described. In fact, the arm fell off as I exited a toll booth. I called ford who is NOT the mfg or installer It was Velvac. Called them and they replaced it for only $247. Two years later the same thing was occurring and again I called Velvac. I also sent pictures of the mirror. This time they sent replacement at no cost!! However, the packing slip did indicate that this time the price was over $400. Give them a call and also send pictures! AND it goes without saying, be businesslike. Good luck.