Firk - Is the neck a single or double socket? (Check your email for clarification as I sent you a couple pictures). I can expand a single socket neck tenon for a fraction of what it costs to buy a replacement neck. With neck and horn in hand, I could make it so tight that you wouldn't even need to use the screw to tighten it into place. Buying a replacement neck is no guarantee it will fit properly anyhow, though if it were from a similar horn of similar vintage it might be ok. Could be an issue with the body receiver, too.