How To Tighten Up Factory Mirrors?

[InfiniteReality]

1 1/2 years ago when the bike was new, I tore it all down to do all the mods... 2 of the mods was the Kanji LED mirror mod and painted my stock mirrors body color. Now one of my mirrors doesn't stay put for longer rides, I have to keep adjusting it to be able to see people behind me. How can I make it "tight" again so it will stay in the same position, I'm at a loss on a solution for it?

Thanks for any help!!
- Del