Dinnu wrote:

I know the bottom cap can come off and there you can see a spring that pulls the assembly into indents. However unsure if there is an adjustment to preload the spring further.

blackwolf wrote:

Yes, the top plug can come out (the easiest way to remove it is to remove the bottom one and then use a long thin thing to push out the top one from below) however the mirror arms are 100% non-adjustable so removing the plug achieves nothing.

In practical terms the only solution to a wobbly arm is to replace the arm.

philippr86 wrote:

Yes, eaxactly as blackwolf said. I also had quite a bit of play in the hinge and thought I just buy new one. So I opted for Allmakes ones only to find out that they did have even more backlash from new. So I took the aftermarket one apart and found that they have been cutting corners in the design. A bit of machining was involved on my lathe, but now I can take them apart, tighten the spring as I wish and all good. Unfortunately I think I did not take any pictures doing this. If I do find any, I will upload them...