It was good to talk with you on the phone today and I am sorry I had to be brief so I could get to a meeting. Long distance pipe repair is never very successful unless you hold the phone up to the pipe. ;-) Here then is an expanded version of what I would look for with a pipe problem such as yours. Once you have the done basics of checking correct wind pressure, looking at the tongue curve, checking to see if any Willis weight has fallen off, and removing the reed tongue to blow out the pipe with compressed air through the open shallot to dislodge all the years of ingested debri, then you can begin the detective work. In reassembling the pipe I would then make sure the shallot shank was tight in the block and the wedge is solidly holding the reed tongue in the correct position. Wedges must be the same angle as the wedge cut in the block for best friction purchase of the reed tongue. Next what is needed is a quick wipe with a crisp new dollar bill between the reed tongue and pressed down shallot to clear any particles of trash that may have been missed. Then the pipe is ready for trial.
I assume the pipes were in storage and you are now just getting them planted on a chest. What most people miss is that pipes are best stored vertically on their chests. When in trays they suffer stress since they are rarely uniformly supported. This causes the seams to sometimes open microscopic holes. And if they were in newsprint the acid may have also opened holes in the pipe body, especially in zinc. So, my first thing to do would be to use masking tape to cover all the seams. Just one little pin hole can make a pipe become very problematical. If the pipe still flies off then it is time to go back to the reed and shallot.
Always start with the shallot. Brass is not dimensionally stable. Shallots made of bent brass plate over mandrels some years ago may change shape. Specifically the shallot face will warp so the reed tongue cannot lay down squarely. Remove the shallot completely and test the shallot with an optical flat. Often you can see light underneath and the shallot must be trued up to again have a flat face. I use machinists bluing on the face around the embouchure then with fine crocus cloth laid down on a machinists granite flat I move the face against to the cloth to see where the high spots are. They wear off first. Worst cases require a flat filing first. The idea is to get all the bluing off for a true flat surface that the reed tongue can deal with. It is my experience that one should always check the shallot before even attempting to work on the reed tongue. A warped shallot will never let you recurve the reed correctly unless you can somehow twist the reed to match the warp in the shallot and it just cannot be done.
So, now we have a solid resonator and a flat true tight shallot but still have a problem. The reed tongue has either a twist, a window, or a flat worn spot. One must check first to see if the reed is windowed. Take the thumb on the shallot and the forefinger on the tongue's lowest end and close the reed with the tuning wire at or near the correct location. If the reed shows any light between the tongue and shallot it is windowed. The worst case is if the window opens between the tuning wire and the wedge as this indicates some amateur voicing has been done. A proper curve will let the tongue be flat on the face. Checking for a tongue twist is done by looking from the bottom of the shallot up toward the pipe, putting a dull pencil at the bottom center of the reed tongue and slowly pushing it down until it touches the shallot face. If the space is parallel through the whole motion then the next thing that may be causing the instability is a worn flat spot on the tongue where the tuning wire has been run up and down too many times. I first try very fine crocus cloth on a granite flat and rub the tongue lightly across it with my finger tips applying pressure the whole length equally. If that does not fix the tongue instability then the most simple cure is to turn the tongue around and curve it in the opposite direction. I like to take a pen knife and run it up and down the two long edges of the tongue. This cleans the metal so I can eyeball the curve by holding the reed sideways to a bright light for reflection and copy the curve I've seen in the opposite direction. Much of reed work is visual as well as aural.
Should all this fail there is no recourse but to make a new tongue which is no big deal but does require the correct tongue stock.
I know I am forgetting a thousand things but I hope my comments helps. I am sure you'll have the pipe fixed by the time the poor man's convention occurs. BTW - can I run the projectors?
Who is also known to fly off speech...