Tower mount and rear view mirror will not tighten

[Mollmat]

I have a 2013 Wakesetter LSV 23 and I cannot tighten the mirror to the tower mount.   It just spins and the screw is tight. I am pretty sure that is the standard tower mount but I do not see a brand on it. I would like to post a picture I don't see how I can attach one. Any suggestions?  

 

Edited June 27, 2018 by Mollmat
Added picture comment

[oldjeep]

Is the screw bottomed out? Maybe try taking it out and adding a couple washers to see. 

[Weaklink]

Some of those mirrors you have to loosen and then push into a channel and THEN tighten-like the PTM edge

 

https://ptmedge.com/faq/

[COOP]

Make sure there is a serrated washer on each side of the tower side mount.