Calboy
.040 Over
ok Calboy there should be some little flats for a spanner on the base of the ball you will need to gently push aside the foam grease retainer assumming they are still there and they are on the ball =side of shifter out of view in your piucture
The grease retainers are coming apart.
But the question is, if I could get a wrench in there to keep it from turning so I can actually tighten that M6 nut, wouldn't I still have that play because of the thickness of the wrench itself?
To accomplish anything I would probably need one of those real thin bicycle spanners which I don't have. I threw them all away the moment I found out Lance Armstrong was a cheater!!