That's some heavy duty hardware

Looks to me like you have to redrill the horn.. . hard to tell with the pic but it looks like the pivet part of the horn is past the hinge line. You want pivet point to be right inline with the hinge.

Also that looks like the 8/32 that goes through the rudder is a bit short. If you have a 3" servo arm you want the distance between the rudder control horns to be as close to 3" as possible. Looks to me like you have an inch of thread showing which is too little.