I usually (but not always) hear a click (steel like I think) from the gearbox
when I releasing the clutch after gearchange. I never hear this click when
changing to 4 or 5, but sometimes I hear it twice when changing to 3
(when I press the clutch and when I releasing it).
Someone told me that it is caused by the worn-out shaft-axle but I cannot
hear it chattering while cornering.
And someone told me that it is caused by the worn-out (bob) carriage (ball head).
So, is there any tips ?

And I'm sorry for my bad English