Thanks for the info. It's odd that an experienced seller with such good feedback would have missed a valve problem, but stuff happens. Too bad, because it is a cool instrument.

BTW, I think this still is a euphonium, but in the category I would label "small euphonium" and which the marketplace often called a baritone. It looks to be mostly conical and the bell is larger than a baritone would have. The American-style horns that I grew up with, made in the 50's and 60's, would MAYBE feel a bit larger to you. Response improved a bit over the years, but as a category these are not as large-feeling/sounding as a horn like the 2280. The Yamaha 321 is in the middle of those classes.

There are a great many old American horns around in varying condition, and they will all feel GENERALLY like this one.

To get a larger feel, the 2280 is hard to match. Have you tried a compensating euphonium? Some tuba players find them stuffy, so I was not sure if such a horn was within the realm of your consideration.