Hi Stefan,
I'm not sure what the problem is, but it looks like to many naked edges.
I would rebuild it like so.

1. Re-create the two profiles.
2. Run "Planer" on the poly-line piece
3, Trim that with the oval.
4. Extrude that.
5 Create two curves and boolean diff, removing the top and bottom pieces.
6. Run the Chamfer tool.

Works for me.





scott