Best Way To Plug Reciever Crack?

The following is a really home grown fix which is only good as a stop gap substitute when you want the horn to play and really can't get the fix done right.

That said;
-Clean the area around and inside of the crack with a good solvent.
-Insert the neck and tighten it to the point where the neck is just held from rotating.
-Back off the clamp screw by a half turn.
-Remove the neck.
-Use a good silicone sealant (clear is probably the best choice for cosmetics) and with a blob on your finger force it into the crack from the inside all the way up to the area of the normal (non extgended) slit where the "dog ears" for the screw are.
-Carefully dab and the sealant from the outside so that it has a good seat perhaps 1/16" on either side of the crack/slit and isn't sticking way out.
-Carefully wipe the sealant from around the crack/slit on the inside of the receiver so that there is nothing except in the slit- and so that that surface of sealant is flush with (or VERY slightly protruding).
-Let it sit for a half hour.
-Very lightly smear the end of the neck tenon with lubricant (grease, whatever) and gently insert it into the neck. The grease will keep the partially cured sealant from adhering to the neck.
-Don't go twisting it or wiggling it; just let the whole thing sit overnight.

The next day the neck should go in and out without leaking and should be able to be tightened with a half turn of the screw. The silicone ought to last for at least six months or so- almost indefinitely if the opening and closing flexion in the neck is confined to a three quarters turn of the screw or less.

I did this on an old Buescher bari when I was stationed in Korea for a year and couldn't find a local tech- worked fine for the duration. Had it fixed properly (replaced the receiver) as soon as I moved to an area with a shop. Aesthetics aside, it probably would have worked forever.

The next step up- still less than ideal- in doing this right involves solder in the crack (soft solder would probably do). Epoxy will lose adhesion and fall out in a couple of weeks in my experience for this application.

Of course, there's probably an underlying issue with the neck tenon fit which caused someone to slit it in the first place. Unless that is fixed you'll still have issues. Good luck.

It's unclear as to whether the extension of the slit is deliberate (on some unknown person's part) or stress induced.

Since there's just not that much going on there that would cause a crack to develop in that way the most likely scenario is the undersized neck tenon that won't tighten and some hack attempting to fix it by widening the slot at the top and extending it downward so it pinches more. If you think about it for even a second I'm sure that no tech anywhere hasn't seen that done more than once.

Fix it right? Sure- drill and fill as Dr. G suggests. Or replace the whole socket. Or silver solder it in case there's some force trying to expand the socket at the base that normal solder wouldn't hold.

And make sure the tenon matches the socket in any case.


But the guy has a school horn in scenic Madagascar and no access to a tech (at least to a tech he's willing to pay) and wants to "make it play".

Chewing gum and teflon tape are really unlikely to work here (the gum might, actually, though even I wouldn't endorse it). Slathering it with grease and stopping up the crack will probably allow it to play.

Suggesting that the guy- probably a high school student- take a torch and a drill to a school horn -and using high temp solder at that- is verging on irresponsible as a recommendation to most high school kids without a background in shop work of some sort.

The easily reversible when it finally gets drug to the shop sealant- or chewing gum- may be ugly as sin and require constant attention to work OK but turning him loose with the torch and machine tools without some confirmation of skills on someone elses horn is like offering Nero the use of your spare gas can.