I keep hearing these 'machine' numbers. 90% of what and measured where. To
characterize a leak you at least need to specify pressure differential and
leak rate. If I brought a horn in to a good technician, how would he measure
it
to determine it needs a valve job. I recently fixed up a horn for a lister
that was unplayable, and he was told by repair people in the Boston area (no
one
was named) that it needed a valve job. The valves were fine, but there was a
very subtle leak doing some strange things acoustically. Fixing the leak,
once it was located, was not a big job, but I don't think anyone would have
questioned the cost of the valve job based on the improvement, even though
unnecessary. All that you need is a stopper for the bell and a bathtub full of
water, and you can check your own horn for leaks. It doesn't take a rocket
scientist to interpret whal streams of bubbles mean. If the valves are really
leaky,
you'll see bubbles coming from the rotor bearings. If you can substantially
stop it by pushing the rotor to the bottom of the casing, tightening the
bearings will help a lot, but it's the side play that has to be removed with a
shrink collet.
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