This is how I fixed mine when they became wobbly. Been a year and still holding strong.
Fixing Those Crappy 13+ Daytona Mirrors
Can't see that this has been answered in the past so for future reference here's how to fix loose 13+ Daytona mirrors. I just ordered a set of Taiwanese knock-offs. They looked and felt like Triumph OEM. Both types, however, use a 'mushroom' rivet to hold the assembly to the fairing mount. This...