Ms.Karen,
Try this for a good solution for this all the time mirror being loose.

Take mirror off Vehicle.
wrap  arm with rag and put in vice.
remove nut spring and bottom mount.
put vice grip on mount stud.
hit vice grip with hammer to remove stud
drill all the way through hole for stud to fit 1/4 x 20 bolt
tap hole
put lock washer on bolt
tighten bolt
mirror will not ever move again from passing truck, and is still
adjustable.
all that you see on top of mirror arm is very end of bolt.
touch it with a dab of black paint it's gone.
I have a new set of mirror's and they slipped from time I put them on.
I fixed forever, and easy.

Good Morning,

Fred

Subject: Passenger Mirror Again
I'm sure this has been discussed many times but how do you prevent the
passenger mirror from moving when a truck passes youor it's windy. I've
taken it apart and there is a spring and a screw with a nut. Do you
tighten the nut as tight as possible to get the mirror to stay in place?
I've tighten it before but that doesn't do the trick unless I need to
really tighten it. There must be an easy fix to this.
84 Westy