I have 3 of the Sullivan units in service. On all 3 I reinforced the area to mount them with 1/8 ply and used four #2 sheet metal screws to hold the bracket on. The wire is glue in with ca only where it goes into the hole. The horizontal section is down about 1/8-3/16 and not glued to the bottom of the rudder. I've used the light spring on all of them. This lessens the strain on the rudder servo and turns the model fine when the plane is moving.