You mean to adjust the clutch... but i think it is ok. Mechanic has also checked it.
Clutch is new, please explain what kind of problem...
By Center axle nut, you mean rear axle bolt and nut? or something else, please elaborate...!
Chain sprocket set is new. I will check it and the bushes too. But the mechanic said its the clutch drum gear and its pinion or something like that or he said it could be the clutch drum wear...