How do I free a wobbly but stuck piston stem?

[Walter Webb]

I inherited a derelict Wm Frank, Chicago Eb Sousaphone, early 20th century, with many battle wounds, most of which I can fix, or learn to fix. It sat on the middle school bandroom shelf for several decades, as the last two band directors decided that kids should learn Bb fingerings only. I traded a good Vito student clarinet for it, plus a Cousenon Eb that is in decent playable condition, although the lead pipe was crudely replaced.

Here's the rub: one of the valve pistons has a wobbly stem, you know, the part that the finger button screw into. It is lodged in the piston body, but will not come out with reasonable force. I have ceased my efforts and avoided the "get a bigger hammer" method of increasing the pull-out force. I want to know if these stems were originally soldered, threaded and screwed in, or what? And, how do I get it out so I can do a thread insert repair, or clean out the green fungus and solder it back into place?

Thanks for any information you can provide,
Walter of Nevada City, CA.

[Dan Schultz]

Those stems were originally soldered in. However... a common way to do a 'quick' fix on stripped threads is to solder them in. There are probably old threads or a blob of solder still keeping the stem from being pulled straight out.

At this point... the easiest fix would be to hold the stem straight and just apply flux and solder it in.

The REAL fix would be to continue to try to unscrew the old stem. Once it's out... repair the threaded hole by restoring the threads by soldering in a piece of brass and drilling/tapping a new hole. Then make a new stem to fit.

[Walter Webb]

Thanks for the advice, gentlemen, but I have decided to cease and desist before causing further damage.
I applied some major force to the piston end with two angled pry bars whilst heating the stem and piston with a small butane torch. Then I twisted and pulled, rotated and yanked (it took 4 arms to do this) and no dice. My conclusion is that the copper-colored piston (the tube-like part with valve holes drilled in it) has a kind of round fitted insert that is pressed and soldered into the top. I believe the stem has a flange on the backside of this and will never come out without taking the piston down to a tube with no top end.

For a derelict souzy with numerous issues, I will hang it on a wall somewhere, or prop it in a window. Someday, somebody might be glad I stopped right here. It's the Hippocratic oath in action. Do no further harm, yet somehow I doubt the world will come beating down my door in search of William Frank Eb Sousaphone parts.

Thanks again, Walter

[Dan Schultz]

Thanks for the advice, gentlemen, but I have decided to cease and desist before causing further damage....

That's probably a good idea, Walter. At this point.... many choices of repairmen are as close as your nearest mailbox! Just send them a known good piston/stem along with your problem one so they can match a new stem.