Stan: First advice: STOP BLOWING IN THE ASI! That's the best way
there is to destroy it, which you might already have done. I've seen
people walk up to a pitot tube and put their mouth to it, and I cringe
at the thought of what they're doing to the internal workings. If you
disconnect the plumbing from the instruments you can check it's
continuity by drawing a slight vacuum on it and seeing if it holds.
I've seen plastic tubing chewed through by mice, and worse yet, I've
seen instruments incorrectly plumbed by someone who was "testing the
system." If neither of these is the problem you probably need to send
the instrument to a qualified shop. Fred