RE: Sig Citabria Build
I did put a tiny drop of thick CA between the plywood strap and the top of each of the blocks that are attached to the servo. This assures that the servo doesn't slip toward the pushrod when it is under pressure from being actuated. Be careful though, you don't want to glue the servo in permently or you won't be able to service it. If you are very careful about getting a good fit between the blocks there is no way the servo can move laterally. The fit cannot squeeze the servo mounting blocks, as that would defeat the flexibility of the groumet mounting system by pushing the blocks tight against the servo. Make the fit between the blocks just tight enough that there is no movement between them.
There is kinda a trick to getting the assembed servo installed. The servo arm must be screwed onto the servo before attaching it to the pushrod. Stick the hook of the pushrod into the hole in the arm and then kinda swing the whole thing around and slide it into the cavity. You will see what I mean when you try to put this all together. The picture might help explain.
Good Luck.