carb cylinder became too small for slide...

[crowvise]

...any ideas why? Going above speed for a few minutes?
My mechanic acquaintance gave me some 320 grit sandpaper and I sanded the inside bore. that helped. I still need to sand some more though. I also broke my float[on/offing the fuel line can't be good(what may be some of the consequences) for the kit].
When I get a new carb would I need a "break in" period? If so how long? I ask this 'cause I can't for the death of me think of anything else that might have caused the binding of the slide.

 

[AussieSteve]

Often these carbs go out-of-round when the top cap is tightened. It seems to distort the bore.

You don't need to 'run in' a carb.