> I have a 24 oz Co2 bottle - it is just about empty at room temperature.
> 
> There is a slight leak at pressure around the bottles pin valve and the
> bottle.  I want to remove the pin valve - fix the leak - and reseal the
> bottle.
> 
> Is anyone out there a professional that can give me assistance or warnings??
> 
> I really do not want to hear from people who are just guessing or have never
> done this.  Thanks all.


I have changed out a few valves and a number of valve stems before.  Stems
are easy, valves are a pain.  If it's leaking between the brass base of
the valve and teh aluminum of the tank, then it has to be removed and
re-sealed.  If the leak is from around the safety nut, tighten the nut.
If leaking frmo the pin, the pin valve may need repair or replacement.

To remove the entire valve:

(1) empty the bottle.  I recommend REMOVING the safety nut to be certain
    it is really empty.  (don't lose the brass disc that is under it)
    This may seem extreme, but if you take that valve off and there is
    any air in there, you've got a 4lb bottlerocket that will go through
    walls.

(2) remove the valve.  easier said than done.  Professionals have a "tank
    vise" they can place the tank in and hold it tightly without damage
    to the tank.  You may have problems holding it strongly enough when
    trying to turn the valve.  It removes in the standard direction,
    counterclockwise.  DO NOT use the safety nut as a point of levarage
    to help turn the valve.  DO NOT use any metal clamp on the tank that
    will cause any kind of dent or crease.  I've always held them by hand,
    but I watched a scary person use a VICE GRIPS to hold a 3.5oz steady,
    and with the scars on that tank, I'd never trust it to be safe.  You
    might be able to use a oil filter removal tool to hold it safely.

(3) remove all glues and tape from the threads of the tank and the valve.
    There may be a yellowish resin on the threads, or what's left of some
    chewed up teflon tape.  It all mus tbe removed, and the threads cleaned.

(4) replace the o-ring.  there is likely an o-ring around the collar of
    the valve.  Replace it with another of the same size.  be sure the
    seating area around the o-ring (on the valve AND tank) is very clean.

(5) wrap a thin layer of teflon tape around the threads of the tank.
    be sure to wrap them CLOCKWISE with the BOTTOM of the valve facing
    you, or the tape will be rolled off as you twist it back into the
    tank.  Don't go wild with it, you only need tape two layers deep,
    so give it 50% overlap on each turn and that will be enough.

(6) put it back on.  If you hare problems getting it on, you might have
    put too much tape on it, only use two layers.  The valve MUST go on
    ALL THE WAY.  If you cannot get the o-ring sealed, it's a severe
    safety hazard to gas up.  Once you have it all the way back on,
    replace the disc and safety nut and it's ready to gas up. :-)


Pin valve leak:

(1a) to repair a bad pin valve you need to remove it from the valve
     body.  If it's a 'tippman' valve, (thin pin with a wider head)
     you can remove it externally.  Otherwise, see above for removing
     valve body from tank.

(1b) If it's a tippman valve, depressurize and remove the nut as above.

(2) note depth of pin, related to top of valve body.  On most valves,
    this depth is adjustable, and will affect your gun.  Too shallow,
    and the depressor in your gun may not open it fully, or at all.
    Too long and it will open early, spraying you with CO2 as you
    are attaching or removing your tank from the gun.  Also too long
    can be a safety hazard (see bottlerocket comment above) though you
    are not likely to adjust it THAT long.

(3) unscrew the valve.  A needle-nose pliers works well on the tippmans.

(4) there will be what amounts to a cup seal.  In many cases, the seal
    simply did not get seated correctly during a fill and then got held
    in place a bit off center.  Letting it sit for a bit outside the tank
    and then replacing it will fix things.

(5) There is sometimes a small black o-ring that gets chowed and will
    obviously need to be replaced.  Hardware stores actually carry
    them. :-)   Go get it and replace it.

(6) screw it back in.  Return it to its original depth, or adjust as
    desired.


Note: repair of pressurized cylinders is probably covered under several
safety regulations, and I would expect requires re-certification of the
tank to legally fill after repair.  If you don't get it re-certified,
(the price of which probably exceeds the cost of the tank) it is
technically illegal to fill.  Just thought you should know.