With the carb slide fuel needle looking like that it's very likely the slide pieces themselves are worn out of spec, that causes excess vibratation and wears the needle like you see.
There are wear limit marks in there somewhere which will tell you if replacement is in order(on the slide I thinK).
'02 KTM 640 Adventure-lowered
"On the road there are no special cases."
Cormack McCarthy-The Crossing
The faster it goes the faster it breaks.
And high performance=high maintenance.