You probably already know about your mirrors but here goes anyway.I was investigating.As usual

.Like to know how things work !.Forward or back (only) adjustment is on the mirror casing (o-k).If it's too tight or too loose just peel back the rubber shroud to reveal the Bolt and Nut then tighten or loosen as required.As for the mirror Glass inside the casing.There are 2 screws in the bottom of the outer mirror casing.Take them out and then the mirror and the mounting it is fitted onto pulls out of the main body to reveal the mechanism inside.It has a nut to tighten or loosen making it easier or more firm to move the mirror glass up down or left to right.I just had to have a look

because i was strugling to move the glass inside the casing.I have now adjusted the tightness of the nut and it is much easier to move the mirror insert left,right,up,down.Hope this info may help others.all the best.Old Nyk.
Jolly Good Show.All the best from Old Nyk in the U.K.
Born Again "OLD" Biker !
My Bikes.
1966 Triumph T100ss --
1984 Kawasaki ZN 1300.Voyager
1996 Suzuki GSX-R 750 SRAD.