Have you ever tried Kazy Glue on your mirror ? If you use it be careful NOT to make skin to skin contact. You might find it to be very uncomfortable to get your fingers apart again.
It will do you no good if you use it on the ball joint. The glue will just "freeze" up any adjustability on the ball joint
Krazy glue must be applied to both surfaces and than pressed together {no tools} .
In a few minutes you'll have a strong fusion .
I hope this will be of some use to repair your mirror.
Sincerely Dieter 55 2 door