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does anyone know the thread size for the screws on an allora tuba? its a rotary valve.

I'd suggest you contact Tom McGrady at Mack Brass. He's a sponsor on this board. I bought a nice French horn from him and a screw broke. He sent me a replacement. He keeps supplies on hand. Maybe the Chinese tubas he markets have screws that would work on your Allora tuba. If so, he could sell you one.

Ace

Allora is another JinBao label, but for WWBW and M&A, or so I have been led to believe. As stated above, Tom McGrady should be able to help you with the part (maybe not a free part because it isn't a Mack Brass horn, but at least sell you one or tell you the size).