Your model of Trracer may differ slightly from mine.  My T's valve tube
is only about 1/4" long beyond the hammer collar, and is tapered.  The
power tube is attached to the hammer.  Some versions of the nelson
design (including the orignal, the 007) have no tube on the hammer -
the valve tube IS the power tube and extends through the hammer.  This
fix is primarily for guns with my Trracer's design. (power tube on the
hammer)

The modi is simple and cheap.  Go to the hardware store and buy a faucet
repair kit - the one with all the black washers in it.  You might want
to grab a pack of single-edge utility razorblades too. (always handy)
When you get home, take apart the Trracer and remove the hammer.  Go
through your washers and find one that has about the same size hole
as the hammer.  If you can't get a close match, select a smaller one
and you will have to trim it up later.  Oh, be sure to select a black
rubber washer.  Find the hardest rubber one if there is a choice.

Take a razor blade and shave off a slice about 1/2 the thickness of
a dime.  This can be done easier if you slowly rotate the washer,
scoring a shallow cut all the way around, and then slice straight
through it following the cut on both sides.  Trim the outside and
inside if necessary, to make a perfect fit with the striking area
inside the depression in the hammer.

Oh, rubber cement, you'll want some of that too.  No hard glues or
other stuff, it must be somewhat pliable.  Make sure the hole in
the washer is the same as (or maybe 1/2mm wider than) the hole in
the hammer.  Glue it into the striking area.  Once dry, assemble
and take to the chronograph.  You WILL need to turn down your
velocity, because your Trracer is now much more gas-efficient. :)
Effect #2 is that the hammer doesn't make much of a sound anymore
when hit hits the valve pin.  Effect #3 is that it gets a better
seal when firing, and doesn't vent much gas out the mechanism
tube as a result. (making noise AND wasting gas)  Effect #4 is
the only negative.  You will notice than your Trracer now cocks
(locks the sear to the bolt) *earlier* than it used to.  It is
possible to cock the Trracer without fully allowing a ball to
drop into the chamber. (making the gun "jam" when you try to
push the pump forward)  This may take a little getting used to;
just make sure you pump all the way back, and if it "jams",
just pull back again to let the ball fall in.

With this mod and a silencer, you can hear a ball whistle as
it travels downrange.  You'll get a little *whump* from the
barrel and a *ting* from the tank as it resonates from the
valve pin getting hit open.