piston alignment - how bad could it be?

[Donn]

The tuba - Pan American Eb Giant Bass, ca. 1926. Beater acquired for $350 if I remember right. Big sweet sound higher up, falls apart below the 2nd ledger line.

The valve alignments: amateur investigation finds the pistons all running low, a minimum of 1/16" in up positions and average of that much down.

Amateur repair using spacers cut from a wine cork results in noticeable improvement, particularly at the low end. This is the kind of "bass tuba" that's built on a contrabass bell and large branches, and the valves show significant wear, so there are going to be some challenges, but Bb and A below the clef are now real notes that I can sustain with some approximation of a pitch. Other trouble notes seem better now, too, though I'll have to play it more to see what I think about that.

So I'm reasonably confident that the alignments really were off by that extravagant amount. What bugs me, though, is, why? The piston tops and caps aren't sparkly clean, but there wasn't 1/16" of dirt in there. Could the cork spacers have soaked up oil and swelled to almost double their original thickness? It's easier to imagine what happened to the felts above the caps, if they just got lost or beaten down maybe it could add up to that much.

[bort]

Well, who know what was actually installed on there?

Years ago, a new player joined a band I was in, and his tuba (at his own admission) sounded awful. I asked if I could try, and it sounded awful for me too. The valve alignments just seemed way off to me (uneven, really loud, really cushioned...). I asked what the deal was, and he said the old ones were worn out, so he replaced them with (literally) whatever he had around. No measuring required?!