Use a long 13mm socket on a U/J or wobble bar to undo the locknut.
And as vern says, adjust the 10mm bolt head by hand so you have play at the arm.
Then tighten lock nut.
That's what i have been trying to do with the tools you list the problem is keeping the 10mm bolt still when i tighten the lock nut it moves with it and reduces the amount of free play.
But i have a long weekend coming up so i will have another go.
