Dave:

It is that "knarled" area where mine is worn out, after 5 years of running. However, mine is knarled higher up. From the positioning of the marks on yours, I would guess that your carb was not fully seated. This will definately cause the engine to suck air. If your engine has the o-ring at the bottom of the throat, where the carb slides in, you may not get a good seal. Don't worry if this is the case though, as the carb body is only about $9.00.

Andy