There is not really any way to tighten up that pivot point,it is spring loaded with ridged washers that control the movement. Most times they just break
Like this as mine did.It is pretty common on ones that are folded a lot or are exposed to a lot of water, the post inside is pot metal and corrodes and fails.
On
Page 4 of that thread the Late J-D did find a work around for the broken arm.
There are a few pictures in that thread and more on
This one.About the only to fix it is to replace the whole thing. They can be ordered from
Velvac that is what I did,replaced both of them.
About that screw on the end of the arm,On a Velvac mirror,there is a adjustment at the end of the arm,use a screwdriver to unscrew the cap, under it you will see inside the opening a hex screw I think a 3/8. turn it to tighten or adjust the mirror head.
