I repair Bachmann train sets and constantly fight the problem of broken air horns. Most times parts department is sold out or no longer available. I don't want to use cast brass. Any help would be appreciated. Mostly I have problems finding single chime horns for F3 F7
Have you looked at Walther's catalog?
Just a guess but I remember Precision Scale some years ago sold brass and plastic parts.
Even a general Google search?
Maybe Shapeways printing? They print a lot of stuff for Bachmann modelers.
Rich