Conn new Wonder Thread size

Ok, so it's my first post and I'm asking for help....that never happens...

Anyway,

My 11-year-old is learning to play, and he's dragged me into the process with him, and as an old Baritone horn player, it's turning out to be a lot of fun. I hate owning stuff I can't work on, at least in a basic fashion, so I've been keeping an eye out for something to learn to work on...

That project has arrived, and in the words of Chief Brody (Jaws): We're gonna need a bigger boat.

I've fallen into a 1922 Conn New Wonder that, despite it's age and travails, is a sweet player.

However, it's the most abused instrument I've seen in a long time-maybe ever. Much of the silver plate is gone from the keywork, and the culprit, in the form of hard red Jeweler's Rouge, lurks in every crevice. Some rocket scientist put this poor thing on a buffing wheel-assembled (and, apparently, with his eyes closed)! I don't care a lot about looks, but how anyone could do this to a horn is beyond me. Look closer and you can see that most of the key barrels in the lower stack (at least) have been swedged.....with lineman's pliers....

Amazingly, leaks are few and minor and it wants badly to play--and, to my inexperienced chops, play easily and well.

...

So much for the history.

My immediate need is related to the fact that the main rod for the lower key stack had (probably) been buggered and cut short, and a new screwdriver slot poorly cut into the [new] end. On removal, one side of the slot departed the rod, and I was extraordinarily lucky to get it out at all. Anyway, I need a new rod. I live in a remote area and have no local resources. I'm an OK gunsmith, and I can fix a carburetor, if that helps... ["Carburetor"; a french word that means, "DON'T MESS WITH IT, STUPID..."]

So, can you direct me to a source for appropriate rod stock? And--most importantly--a threading die in the appropriate thread (which I don't know what it is....)?

My hardware store stops at 1/4-20 in terms of being able to ID a thread size, so any educated guesses on that are welcome as well.

Obviously, as I get deeper into this project, there's gonna be more issues but I'm new at this and would like to get it together so I can play it a bit and get to know her before I make any further ugly discoveries. It's sure a lot better horn than the ex-rental Jupiter I'm using now...

Thanks for your help!

Steve Alley