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I am interested in knowing if anyone has any experience with one of these horns. I'm trying to decide if I should spend the money to repair it. I've never been able to play it because of some significant leaks. I'm pretty sure I've isolated the leaking spots and would like some information on a cheap way to patch them so that I can test play it and then make a decision on having it repaired correctly.
The sousaphone is in good shape: no major dents, and all of the slides and valves work. I was told it is a military issue instrument used right after WWII.

I have one, but because it is so @#%$# big, I have learned NOT to march with it!!!

It produces a very broad (6/4'ish) sound, which I like a lot, for band playing. There are some pitch issues with mine, but in fairness, I don't get the chance to play it often enough.

I played a Buescher three valved sousaphone in high school. My dad took the sousaphone to where he worked at the Santa Fe Railroad Shops in San Bernardino and a colleague of his used a combination of soldering and brazing to get everything just right. You are right, it was quite a heavy horn (over 50 pounds) but after marching with it for one block, my shoulder was numb enough that it didn't matter. It had a nice, big, clean tone.

Bloke, would the serial number enable me to identify if it was a "real" Buescher vs a johnny -come -lately horn? The serial number is 148686. I will try to find a way to measure the bore.
I'm really trying to decide if I should repair and keep this horn or my Wurlitzer helicon which is already in fine playing condition. I don't think I would use either one very often but would like to keep the better of the two for the occasions where it would be nice to have this type of horn.