Ab3 and F#3 Difficult Notes?

[sakuramimato]

I noticed that playing Ab and F# in the third octave
comes out stifled and I''m not even going to touch on fourth octave B-natural
(I use B-foot flute). o_o When I play those three notes, they always seem to
come out stifled and airy unlike the notes that precede and proceed them. Is
that natural? After one year, my flute''s had some serious wear (missing a
cork strip in the foot joint), etc. It might be my fingering with the open
holes. Any similar experiences with having difficulty on those notes? I can
register them perfectly fine, but on fast runs and quick scale runs, they seem
to be too airy for like or drop an octave, sometimes don''t even register at
all.