smokingwreckage

Control linkages can never have zero slop. A friction fit will risk over-powering the servo, especially when the pin or wire going through the servo arm or control horn is not perpendicular to the surface it goes through. Shorter pushrods "rock" more in the holes than longer pushrods. Even changing temperatures can affect the amount of play in a linkage. Since some play is inevitable, the further from the servo arm screw or hinge the pushrod link is hooked up, the less free movement of the control surface is available for flutter.

To minimize or prevent flutter, set the link as far out on the control horn as possible, then set the throw by attachment position on the servo arm. If the link at the servo arm is not in one of the two outermost holes, change to a longer control horn and start over with adjustments.

I never use anything but 100% EPA. Higher EPA provides very little increase in travel, and lower EPA wastes servo power. If EPA is necessary, you could have used a smaller, cheaper, and lighter servo, and saved money while having a lighter, better flying airplane.

This applies only too control surfaces. I always use the innermost servo arm hole and outermost nose gear arm hole to reduce turn radius as much as possible, and usually still have too much. I use the outermost hole on throttle arm, and whatever servo arm hole provides full servo travel with the best resolution--I want full throttle to be just barely full, and idle to be idle with just enough extra travel for the engine kill feature to work properly.