There are smarter people than I that will respond, but since I am the first, I will through in my 2 cents worth ...

How far along the length of the aileron is the servo installed and what is that position relative to the push rod going up to the top aileron? My thinking is that there may be some flex going on between the servo in the bottom wing and the top aileron. Adding servos to the top wing is certainly the most direct solution and probably would not require that much surgery. So far, I have not had to do that on one of my bipes, but yah never know. I don't know what I would do with the push rod though. Best left off, but what about scale? Just wouldn't look right.

Good luck finding the right solution.

Bedford