Manifold pressure gauge problem

The manifold pressure gauge in my Super D is a pain. More acurately,
it's the line that connects it to the engine. Ten minutes of
aerobatics, and I can't get any kind of reliable reading; it just
sticks wherever.

It's easy to fix. A shot of air into the line (back toward the
engine, of course) and it's good to go, but this is becoming a real
bother. Can anyone tell me if there's a true fix for this, or am I
just doomed to blowing the line clean after every flight that I take
her inverted (i.e., as often as possible. :-)

Thanks,

-Dave Russell
8KCAB