I have three Reedy LP servos for touring car.

Horn going on is a little snug. I put some chap stick on the splines, push the horn on a bit, then used the screw to pull the horn on the rest of the way. Fits nice a snug.

Imagine having to swap horns. I'm scared to remove the one I finally got on, feels like the servo is gonna pull apart.

I've now done some more grinding and modding. Got a decent fit on horn. I can expect the same if I ever change it.