blow bends in upper register of diatonic

["Jason Paul Stolaruk" <stolaruk@xxxxxxxxxxxxx>]

Hey all,
After about 8 years of playing blues harp, I've gotten quite good at producing
draw bends and controlling them.  However, blow bends in the upper register
remain an entirely different beast that I haven't yet tamed.  (This likely has
to do with the fact that I don't play the upper register as much as I could).
In any case, I could use some hints and tips about how to produce blow bends
and how to control them.
First, I heard a player in a club who was bending his blow notes like mad, and
I asked him how he was doing it.  "What are you doing with your tongue?" I
asked.  He insisted that his bends were coming from his diaphragm.  This
completely baffled me.  I typically produce bends by cutting off the air flow
through my nose and moving the back of my tongue up towards the roof of my
mouth (at least that's what I think I'm doing!)  I know how to use my diaphragm
to make a nice tremelo effect, but that's all.  (Any comments on this?)  As for
me, I have been using almost the same technique (that I use to get a draw bend)
to produce blow bends, with some success.  I find that I often have to blow
unusually hard to produce a blow bend.  It's not too difficult to get a blow
bend from hole 9 on a harp that is tuned to a key whose pitches are relatively
low (A or G, for example).  But I'm having trouble with hole 10 and other
holes, and on some harps (F, for example), I can't make anything happen.
Any tips?  THANK YOU!